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ERTS Release Notes

otp_appnotes nil
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This document describes the changes made to the ERTS application.

## Erts 12.3.2.14

### Fixed Bugs and Malfunctions

Fix bug causing "magic" references in a compressed ETS table to not keep the referred object alive. The symptom would be the referred object being garbage collected prematurely and the reference appearing stale, not referring to anything. Examples of such magically referred objects are atomics and NIF resources.

Own Id: OTP-18732 Aux Id: GH-7444, PR-7458

The cleanup operation of not yet delivered signals to a terminated process yielded excessively.

Own Id: OTP-18752 Aux Id: PR-7633

If the external term format encoding of an argument list part of a distributed spawn operation was faulty, the newly spawned remote process could misbehave. The misbehavior included hanging or interpret an incoming message as an argument list to use. This was very unlikely to happen unless using an alternate implementation of the distribution protocol which made a faulty encoding of the argument list. The child process will now detect this error and terminate before executing the user specified code.

Own Id: OTP-18790 Aux Id: PR-7742

Fix bugs where if the body of a matchspec would return a map with a variable ('$1', '$_' etc) as one of the keys or values and the variable was not an immidiate, the term would not be copied to the receiving processes heap. This would later corrupt the term in the table as the GC could place move markers in it, which in turn would cause the VM to crash.

Bug has been present for since OTP 17.0.

Own Id: OTP-18797 Aux Id: PR-7712 GH-7683

## Erts 12.3.2.13

### Fixed Bugs and Malfunctions

The following functions are now much faster when given a long list or binary:

erlang:list_to_integer/1 erlang:binary_to_integer/1 erlang:binary_to_integer/2 erlang:list_to_integer/2 string:to_integer/1

Own Id: OTP-18659 Aux Id: PR-7426

## Erts 12.3.2.12

### Fixed Bugs and Malfunctions

In rare circumstances, bit syntax matching of an invalid code point for a utf32 would crash the runtime system.

Own Id: OTP-18560

If a runtime system which was starting the distribution already had existing pids, ports, or references referring to a node with the same nodename/creation pair that the runtime system was about to use, these already existing pids, ports, or references would not work as expected in various situations after the node had gone alive. This could only occur if the runtime system was communicated such pids, ports, or references prior to the distribution was started. That is, it was extremely unlikely to happen unless the distribution was started dynamically and was even then very unlikely to happen. The runtime system now checks for already existing pids, ports, and references with the same nodename/creation pair that it is about to use. If such are found another creation will be chosen in order to avoid these issues.

Own Id: OTP-18570 Aux Id: PR-7190

Constructing a binary segment not aligned with a byte boundary, with a size not fitting in 31 bits, and with a value not fitting in a 64-bit word could crash the runtime system.

Own Id: OTP-18597

### Improvements and New Features

Further robustify implementation of large maps (> 32 keys). Keys that happen to have same internal 32-bit hash values are now put in collision nodes which are traversed with linear search. This removes the demand for the internal hash function when salted to eventually produce different hashes for all possible pairs of unequal terms.

Own Id: OTP-18569

## Erts 12.3.2.11

### Fixed Bugs and Malfunctions

Fix bug sometimes causing emulator crash at node shutdown when there are pending connections. Only seen when running duel distribution protocols, inet_drv and inet_tls_dist.

Own Id: OTP-18243 Aux Id: GH-6247, PR-6258

Fix bug in binary_to_term (and distributed receive) when decoding a large map (>32 keys) with unsorted small maps (<= 32) as keys of the large map.

This was only a problem if the term was encoded by erl_interface, jinterface or otherwise, as the VM itself always encodes small maps with sorted keys.

The "binary_to_term" would appear as successful but the created large map was internally inconsistent. The smaller key-maps could not be found with maps:get and friends. Other operations such as map compare and merge could probably also give incorrect results.

Own Id: OTP-18343 Aux Id: GH-6496

Implementations of the call() driver callback that returned a faulty encoded result could cause a memory leak and could cause invalid data on the heap of the processes calling erlang:port_call/3.

Own Id: OTP-18525 Aux Id: PR-7049

Aliases created in combination with a monitor using the {alias, explicit_unalias} option stopped working from remote nodes when a 'DOWN' signal had been received due to the monitor or if the monitor was removed using the erlang:demonitor() BIF.

This bug was introduced in OTP 24.3.4.10 and OTP 25.3.

Own Id: OTP-18557 Aux Id: PR-7131, OTP-18496

## Erts 12.3.2.10

### Fixed Bugs and Malfunctions

Active process aliases of a process at its termination leaked memory.

Own Id: OTP-18496 Aux Id: GH-6947, PR-6953

## Erts 12.3.2.9

### Fixed Bugs and Malfunctions

process_info(Pid, status) when Pid /= self() could return an erroneous result.

Own Id: OTP-18421 Aux Id: PR-6806

In rare circumstances, when a process exceeded its allowed heap size set by option max_heap_size, it would not be killed as it should be, but instead enter a kind of zombie state it would never get out of.

Own Id: OTP-18463 Aux Id: PR-6858

## Erts 12.3.2.8

### Fixed Bugs and Malfunctions

Fixed a bug in selective receive optimization that could crash 32-bit emulators.

Own Id: OTP-18383 Aux Id: ERIERL-905

A race condition which was very rarely triggered could cause the signal queue of a process to become inconsistent causing the runtime system to crash.

Own Id: OTP-18388 Aux Id: OTP-17462, PR-6662

## Erts 12.3.2.7

### Fixed Bugs and Malfunctions

Spec for function net:if_names/0 incorrect

Own Id: OTP-18296 Aux Id: OTP-16464

Fix bug in binary_to_term decoding a binary term 2Gbyte or larger.

Own Id: OTP-18306 Aux Id: GH-6393, PR-6401

Fix list_to_atom/1 for negative code points. Could either return with a positive code point or fail with an incorrect exception.

Own Id: OTP-18321

Fix bug in binary_to_term decoding a list of length 1G or longer.

Own Id: OTP-18328 Aux Id: GH-6439, PR-6440

## Erts 12.3.2.6

### Fixed Bugs and Malfunctions

Notifications about available distribution data sent to distribution controller processes could be lost. Distribution controller processes can be used when implementing an alternative distribution carrier. The default distribution over tcp was not effected and the bug was also not present on x86/x86_64 platforms.

Own Id: OTP-18258 Aux Id: GH-6309, PR-6324

## Erts 12.3.2.5

### Fixed Bugs and Malfunctions

Fix writing and reading of more than 2 GB in a single read/write operation on macOS. Before this fix attempting to read/write more than 2GB would result in {error,einval}.

Own Id: OTP-18222 Aux Id: PR-6248 GH-6242

## Erts 12.3.2.4

### Fixed Bugs and Malfunctions

Fix bug causing ets:info (and sometimes ets:whereis) to return 'undefined' for an existing table if a concurrent process were doing ets:insert with a long list on the same table.

Own Id: OTP-18218 Aux Id: ERIERL-855

## Erts 12.3.2.3

### Fixed Bugs and Malfunctions

Fix faulty distribution encoding of terms with either

a fun with bit-string or export-fun in its environment when encoded toward a not yet established (pending) connection or a fun with a binary/bitstring, in its environment, referring to an off-heap binary (larger than 64 bytes).

The symptom could be failed decoding on the receiving side leading to aborted connection. Fix OTP-18093 is a workaround for theses bugs that makes the VM accepts such faulty encoded funs.

The first encoding bug toward pending connection exists only in OTP 23 and 24, but the second one exists also on OTP 25.

Own Id: OTP-18104 Aux Id: OTP-18093

Distributed exit signals could be lost under the following conditions:

An exit signal from a parent process to a child process was lost if:

the parent process terminated before the spawn request that created the child had completed,

the spawn request set up a link between parent and child

the spawn request was distributed, and

the exit reason was larger than one machine word.

Loss of a connection over which a not yet completed spawn request was ongoing could cause loss of exit signals. Such loss of exit signals was very rare. Besides the above described connection loss also the following conditions had to be satisfied:

The spawn request that was interrupted by the connection loss also had to set up a link between the parent process and the child process.

The parent process that issued the spawn request also had to be terminating while the spawn request was interrupted by the connection loss.

The same parent process also had to have made other spawn requests to other nodes than to the node to which the connection was lost.

These spawn requests to the other nodes also had to set up links.

These spawn requests to the other nodes also had to be not yet completed at the time of the connection loss. That is, the spawn reply from the child process had not yet reached the parent process.

If all the conditions above were met, exit signals to the children spawned due to the above described spawn requests to other nodes could be lost.

The above bug also caused a significant memory leak when it was triggered since the destruction of the parent process never completed.

Own Id: OTP-18164 Aux Id: PR-6114

A race could cause process_info(Pid, message_queue_len) on other processes to return invalid results.

Own Id: OTP-18169 Aux Id: PR-6134

Fixed reduction counting for handling process system tasks.

Own Id: OTP-18170 Aux Id: PR-6135

Priority elevation of terminating processes did not work which could cause execution of such processes to be delayed.

Own Id: OTP-18175 Aux Id: PR-6142

An unlink operation made by a process that terminated before the unlink operation completed, i.e., before it had received an unlink-ack signal from the linked process, caused an exit signal to erroneously be sent from the terminating process to the process being unlinked. This exit signal would most often be ignored by the receiver, but if the receiver of the exit signal concurrently set up a new link, it could receive the exit signal with the actual exit reason of the terminating process instead of a noproc exit reason. It is however very hard to detect that this has happened and has no obvious negative consequences, so it should be considered harmless.

A distributed unlink-ack signal received by a terminating process was also not properly removed which could cause a minor memory leak.

Own Id: OTP-18177 Aux Id: PR-6150

The monitor/3 BIF did not apply options to the created monitor if the target process or port did not exist. That is, the corresponding down message would get a `DOWN` tag even if a custom tag had been set, and the returned reference was not an alias even if the alias option had been passed.

Own Id: OTP-18190 Aux Id: GH-6185, PR-6209

The erlang:monotonic_time/1, erlang:system_time/1, erlang:time_offset/1, and os:system_time/1 BIFs erroneously failed when passed the argument native.

Own Id: OTP-18197 Aux Id: GH-6165, PR-6213

## Erts 12.3.2.2

### Fixed Bugs and Malfunctions

Fixed emulator crash that could happen during crashdump generation of ETS tables with options ordered_set and {write_concurrency,true}.

Own Id: OTP-18144 Aux Id: GH-5981

## Erts 12.3.2.1

### Fixed Bugs and Malfunctions

Accept funs (NEW_FUN_EXT) with incorrectly encoded size field. This is a workaround for a bug (OTP-18104) existing in OTP 23 and 24 that could cause incorrect size fields in certain cases. The emulator does not use the decoded size field, but erl_interface still does and is not helped by this workaround.

Own Id: OTP-18093 Aux Id: OTP-18104, PR-5987

The zlib built in to the runtime system has been updated to version 1.2.12. (Note that on most platforms, the platform's own zlib is used.)

Own Id: OTP-18123 Aux Id: GH-5994

## Erts 12.3.2

### Fixed Bugs and Malfunctions

Let EPMD tolerate failure when binding to IPv4/IPv6 loopback intefaces in addition to user-supplied addresses via ERL_EPMD_ADDRESS or the -address option. This can happen, for example, if the host system has ipv6 disabled via the disable_ipv6 sysctl.

Own Id: OTP-17970 Aux Id: PR-5762

Fixed a rare bug in binary_to_term/1, enif_make_map_from_arrays, erl_drv_send_term, and Erlang distribution that could crash the emulator.

Own Id: OTP-18027

Fixed a rare race in persistent_term:get/1,2 that could cause it to return the value of another key.

Own Id: OTP-18065 Aux Id: GH-5908

Fix bug where the process message queue was left in an inconsistent state when changing from on_heap to off_heap message queue data causing the GC to segfault.

Own Id: OTP-18075 Aux Id: PR-5927

Fix functions that convert universal to localtime (such as erlang:localtime/0 and erlang:universaltime_to_localtime/1) to fetch the correct localtime if it is changed after the start of the VM.

Own Id: OTP-18076 Aux Id: ERIERL-802 PR-5905

Fix memory leak when a process doing a distributed fragmented send is sent an exit signal. Before this fix the receiving node would be left with an incomplete message that would remain until the nodes were disconnected. The bug has existed since Erlang/OTP 21.

Own Id: OTP-18077 Aux Id: GH-5876 PR-5892

Corrected the behaviour of the shutdown function when using with the inet_backend = socket. It was not sufficiently compatible with the "old" gen_tcp.

Own Id: OTP-18080 Aux Id: GH-5930

## Erts 12.3.1

### Fixed Bugs and Malfunctions

erlang:open_port({spawn, _},_) has been fixed on Windows to handle whitespace characters in the path correctly.

This could, for example, cause execution of the resolver helper program inet_gethost to fail and instead possibly execute a different program.

Own Id: OTP-17978 Aux Id: OTP-17958

Fix race condition when creating crash dump that could cause multiple threads to race when writing the initial information in a crash dump.

The race condition was introduced in erts-12.2 (Erlang/OTP 24.2).

Own Id: OTP-17993 Aux Id: PR-5806

Fix Erlang monotonic time on MacOS. Previously used OS monotonic time primitive on MacOS is buggy and will not be used anymore. It has been replaced with usage of another OS monotonic time primitive that does not appear to be buggy.

Own Id: OTP-17998 Aux Id: PR-5825, GH-5554

## Erts 12.3

### Fixed Bugs and Malfunctions

Fixed a bug in the x86 JIT that might cause floating point instructions to wrongly throw an exception.

Own Id: OTP-17822

Preserve correct nodedown_reason if supervised distribution controller processes exit with {shutdown, Reason}.

Own Id: OTP-17838 Aux Id: PR-5748

Handling of send_timeout for gen_tcp has been corrected so that the timeout is honored also when sending 0 bytes.

Own Id: OTP-17840

By default global does not take any actions to restore a fully connected network when connections are lost due to network issues. This is problematic for all applications expecting a fully connected network to be provided, such as for example mnesia, but also for global itself. A network of overlapping partitions might cause the internal state of global to become inconsistent. Such an inconsistency can remain even after such partitions have been brought together to form a fully connected network again. The effect on other applications that expects that a fully connected network is maintained may vary, but they might misbehave in very subtle hard to detect ways during such a partitioning.

In order to prevent such issues, we have introduced a prevent overlapping partitions fix which can be enabled using the prevent_overlapping_partitions kernel(6) parameter. When this fix has been enabled, global will actively disconnect from nodes that reports that they have lost connections to other nodes. This will cause fully connected partitions to form instead of leaving the network in a state with overlapping partitions. Note that this fix has to be enabled on all nodes in the network in order to work properly. Since this quite substantially changes the behavior, this fix is currently disabled by default. Since you might get hard to detect issues without this fix you are, however, strongly advised to enable this fix in order to avoid issues such as the ones described above. As of OTP 25 this fix will become enabled by default.

Own Id: OTP-17843 Aux Id: ERIERL-732, PR-5611

Corrected the type specification of erlang:seq_trace/2.

Own Id: OTP-17900 Aux Id: GH-5667

Fix memory leak when tracing on running on a process that only handle system tasks or non-message signals (for example process_info requests).

Own Id: OTP-17904 Aux Id: ERIERL-757

### Improvements and New Features

Add support for using socket:sockaddr_in() and socket:sockaddr_in6() when using gen_sctp, gen_tcp and gen_udp. This will make it possible to use Link Local IPv6 addresses.

Own Id: OTP-17455 Aux Id: GH-4852

Show on_load failure reasons in embedded mode.

Own Id: OTP-17718 Aux Id: PR-5199

Compile date saved in the Erlang VM executable has been removed.

Own Id: OTP-17891 Aux Id: PR-5589

Improve documentation for the dynamic node name feature.

Own Id: OTP-17918

## Erts 12.2.1

### Fixed Bugs and Malfunctions

Fixed a memory leak in file:read_file_info/2 and file:read_file/1 on Windows.

Own Id: OTP-17827 Aux Id: GH-5527

Fix GC emulator crash when spawn_request was used when message tracing was enabled.

Own Id: OTP-17871 Aux Id: PR-5612

## Erts 12.2

### Fixed Bugs and Malfunctions

When matching and constructing utf16 segments in the binary syntax, the native flag would be ignored. That is, the endian would always be big endian even on a little-endian computer (almost all modern computers).

Own Id: OTP-17713

Fix the help printout of +JPperf.

Own Id: OTP-17749 Aux Id: PR-5378 GH-5361

Fix bug that could cause Erlang to deadlock during creation of an Erlang crash dump.

Own Id: OTP-17751 Aux Id: PR-5315

Fixed C++ build errors on some aarch64 platforms.

Own Id: OTP-17763 Aux Id: GH-5351

For macOS, the Info.plist file embedded in the runtime system now only contains the absolute minimum amount of information needed for the web view in wx to work towards localhost. The other fields have been removed, allowing an application packaged in a bundle to specify the application name and other parameter in its own Info.plist file.

Own Id: OTP-17785 Aux Id: PR-5393

Fix bug in internal stacks (WSTACK and ESTACK) used by term_to_binary/2 to encode terms. The bug could cause a segfault if a very very large map was to be encoded with the deterministic option given.

Own Id: OTP-17804 Aux Id: PR-5372

Improve the error printout when open_port/2 fails because of invalid arguments.

Own Id: OTP-17805 Aux Id: PR-5406

Fix bug in crash dumps where the stackframe of a process would be printed using an incorrect format.

Crash dump viewer has also been fixed to be able read the broken stack format.

The bug has existed since Erlang/OTP 23.0.

Own Id: OTP-17814 Aux Id: PR-5462

### Improvements and New Features

An option for enabling dirty scheduler specific allocator instances has been introduced. By default such allocator instances are disabled. For more information see the documentation of the +Mdai erl command line argument.

Own Id: OTP-17363 Aux Id: GH-4728, PR-5187

Minor optimization of receive markers in message queues.

Own Id: OTP-17673 Aux Id: OTP-16226

All predefined types have been added to the erlang module together with documentation.

Any reference to a predefined type now links to that documentation so that the user can view it.

Own Id: OTP-17689 Aux Id: PR-5292

Suppress a code checker warning caused by debug builds of YCF. YCF tries to get a conservative estimate of the bottom of the stack by reading and returning a call stack allocated variable.

Own Id: OTP-17719

Add file and product properties to erl.exe and werl.exe.

Own Id: OTP-17724 Aux Id: ERL-1224

Micro optimization in bitstring append operations.

Own Id: OTP-17760 Aux Id: ERIERL-725, PR-5414

Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.

This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.

This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).

Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

## Erts 12.1.5

### Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.

Own Id: OTP-17735 Aux Id: GH-5339

The fix for Linux's behaviour when reconnecting an UDP socket in PR-5120 released in OTP-24.1.2 has been refined to only dissolve the socket's connection before a connect if the socket is already connected, that is: only for a reconnect.

This allows code to open a socket with an ephemeral port, get the port number and connect; without the port number changing (on Linux). This turned out to have at least one valid use case (besides test cases).

Should one reconnect the socket then the port number may change, on Linux; it is a known quirk, which can be worked around by binding to a specific port number when opening the socket. If you can do without an ephemeral port, that is...

Own Id: OTP-17736 Aux Id: GH-5279, PR-5120, OTP-17559

Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:

EXIT signals with exit reasons of one word size. DOWN signals with exit reasons of one word size. demonitor signals from a terminating process. unlink_ack signals on OTP 23 and 24. spawn_reply signals on OTP 23 and 24.

Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

## Erts 12.1.4

### Fixed Bugs and Malfunctions

Fix bug where a gen_tcp write error that happened during a delayed_send would cause a use after free segfault.

Own Id: OTP-17731 Aux Id: PR-5285

Fix x86 JIT bug where a rem instruction could cause a segfault if given values that would cause an badarith exception.

Own Id: OTP-17732 Aux Id: PR-5331 ERIERL-664

## Erts 12.1.3

### Fixed Bugs and Malfunctions

Reduction counter was not updated before and after doing apply operations on the runtime system with the jit enabled. This caused reduction counting to get out of sync if a garbage collection was made as part of the apply operation.

Own Id: OTP-17675

This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.

Own Id: OTP-17677

When attempting to construct a binary with an segment having an illegal type for the size (e.g. an atom), there could be an unnecessary memory allocation (and subsequent deallocation) before the operation failed. Amended to fail before allocating any memory for the binary.

Own Id: OTP-17686

Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.

The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.

Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.

Own Id: OTP-17700 Aux Id: GH-5271, PR-5273

Fixed a crash when inspecting the stack trace of an exception raised at a very high line number.

This bug was introduced in OTP 24.

Own Id: OTP-17712

The following two bugs that caused erlang:demonitor() to behave erroneously have been fixed. The bugs were only triggered if the monitor that was removed by demonitor() had previously been created simultaneously as a monitor and as an alias.

A demonitor operation on a monitor created using the {alias, reply_demonitor} option erroneously behaved as if the {alias, explicit_unalias} option had been used. A demonitor operation did not prevent a corresponding 'DOWN' message from being delivered if the monitor reference was kept as an active alias after the operation. This could only occur if the monitored process simultaneously terminated before the demonitor signal reached it, and the exit reason was not an immediate term. That is, a term larger than one machine word.

Own Id: OTP-17722 Aux Id: GH-5310, PR-5313

## Erts 12.1.2

### Improvements and New Features

The python scripts that existed in erts/lib_src/yielding_c_fun/lib/tiny_regex_c/scripts had a license that was incompatible with Erlang/OTP's license. This ticket removes these scripts that were not used by us.

Own Id: OTP-17658

## Erts 12.1.1

### Fixed Bugs and Malfunctions

A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similiar race could also cause a memory leak when receiving an unlink signal.

Own Id: OTP-17642 Aux Id: PR-5248

A user defined tag on a monitor message could cause the runtime system to crash when the monitor message had been received.

Own Id: OTP-17646 Aux Id: GH-5221, PR-5232

A call to erlang:demonitor(Ref) where the reference Ref referred to an active alias, but not an active monitor, caused the runtime system to crash.

Own Id: OTP-17647 Aux Id: GH-5225, PR-5230

The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.

On OTP 24 this could also cause the whole runtime system to crash.

Own Id: OTP-17651 Aux Id: GH-5235, PR-5244

Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.

Own Id: OTP-17665 Aux Id: PR-5248

## Erts 12.1

### Fixed Bugs and Malfunctions

Atoms with Unicode code points greater than 255 (for example Greek or Cyrillic characters) would not be displayed correctly by crashdump_viewer.

Own Id: OTP-17377

Fix rare minor memory leak related to jit code loading.

Own Id: OTP-17445 Aux Id: PR-4843

The extended error information has been corrected and improved for the following BIFs: binary_to_existing_atom/2, list_to_existing_atom/1, erlang:send_after/{3,4}, and erlang:start_timer/{3,4}.

Own Id: OTP-17449 Aux Id: GH-4900

Fix bug provoked when building with gcc 10 and link time optimization (-flto), causing Erlang compiler to crash. Bug exists since OTP-24.0.

Own Id: OTP-17477 Aux Id: GH-4846, PR-4894

Corrected bugs where builds were not reducible even when the deterministic option was given. In particular, modules with map literals with more than 32 elements could cause this problem.

As part of this fix, the term_to_binary BIF now accepts the option deterministic.

Own Id: OTP-17495 Aux Id: PR-5153

After an exception has been caught in a process, the stack trace would be kept in the process longer than necessary.

Own Id: OTP-17512

Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.

Own Id: OTP-17513 Aux Id: GH-4964, PR-5015

The configure test for --disable-esock-socket-registry has been corrected so disabling now works.

Own Id: OTP-17539

init:stop() no longer unloads loaded code before terminating the runtime system. On systems with slow CPUs (such as Raspberry PI Zero), that can significantly speed up termination of the runtime system.

Own Id: OTP-17542 Aux Id: GH-5031, PR-5032

Fixed match specifications that use maps in either the guard or the body to work properly.

With this fix both keys and values in maps can be expressions.

Various other crashes and bugs when using maps in match specifications have also been fixed.

Own Id: OTP-17567 Aux Id: PR-4915 PR-5115

Parsing of the result value in the native DNS resolver has been made more defensive against incorrect results.

Own Id: OTP-17578 Aux Id: ERIERL-683

When binary_to_term/2 failed, the extended error information would always blame the second argument even if the actual error was in the first argument.

Own Id: OTP-17591 Aux Id: GH-5171

On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17604

A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).

Own Id: OTP-17628

### Improvements and New Features

Optimize memory usage of erts internal processes used during code loading/purging by hibernating them after a long time of inactivity.

Own Id: OTP-17426 Aux Id: PR-4785

Add the type erlang:stacktrace/0.

Own Id: OTP-17453 Aux Id: PR-4764

The arity argument of error/2,3 can now be none to indicate that the calling functions arity should be used.

Own Id: OTP-17456 Aux Id: PR-4764

Optimize match spec compiler for immediate (single word) constant terms.

Own Id: OTP-17469

Functions erlang:set_cookie(Cookie) and erlang:get_cookie(Node) have been added for completeness and to facilitate configuring distributed nodes with different cookies.

The documentation regarding distribution cookies has been improved to be less vague.

Own Id: OTP-17538 Aux Id: GH-5063, PR-5111

A workaround has been implemented for Linux's quirky behaviour to not adjust the source IP address when connecting a connected (reconnecing) UDP socket.

The workaround is to, on Linux, always dissolve any connection before connecting an UDP socket.

Own Id: OTP-17559 Aux Id: GH-5092, PR-5120

The internal documentation for how to use Yielding C Fun (YCF) has been updated to contain text about best practices for using YCF for ERTS.

Own Id: OTP-17596

Optimize garbage collection for processes with large number of binaries, funs and/or external pids/ports/refs.

Own Id: OTP-17602 Aux Id: PR-5149

## Erts 12.0.4

### Fixed Bugs and Malfunctions

A call to the process_info() BIF could end up hanging for ever due to a bug introduced when the new selective receive optimization was introduced in OTP 24.0. Note that this bug only effects process_info().

Own Id: OTP-17548 Aux Id: PR-5078, OTP-10391

Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.

Own Id: OTP-17560 Aux Id: GH-5116

Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.

Own Id: OTP-17568 Aux Id: PR-4940

Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.

This bug has existed since Erlang/OTP 20.0.

Own Id: OTP-17585 Aux Id: GH-5150

binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17594

## Erts 12.0.3

### Fixed Bugs and Malfunctions

A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.

Own Id: OTP-17472 Aux Id: PR-4932

Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.

The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.

Own Id: OTP-17493

Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.

Own Id: OTP-17500 Aux Id: GH-4809

## Erts 12.0.2

### Fixed Bugs and Malfunctions

Not yet handled alias-message signals in the signal queue at the time when a garbage collection was performed could cause a memory corruption which in turn could result in a crash of the runtime system. This bug was introduced in OTP 24.0.

Own Id: OTP-17431 Aux Id: GH-4858, PR-4870, OTP-16718

Fixed bug when using external pids/ports in keys of big maps (> 32). Could cause runtime crash. Bug exists since OTP 24.0.

Own Id: OTP-17436 Aux Id: PR-4875

After a node restart with init:restart/0,1, the module socket was not usable because supporting tables had been cleared and not re-initialized. This has now been fixed.

Handling of the "." domain as a search domain was incorrect and caused a crash in the DNS resolver inet_res, which has now been fixed.

Own Id: OTP-17439 Aux Id: GH-4827, PR-4888, GH-4838

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).

Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

Bug fixes and code cleanup for the new socket implementation, such as:

Assertions on the result of demonitoring has been added in the NIF code, where appropriate.

Internal state handling for socket close in the NIF code has been reviewed.

Looping over close() for EINTR in the NIF code has been removed, since it is strongly discouraged on Linux and Posix is not clear about if it is allowed.

The inet_backend temporary socket option for legacy gen_tcp sockets has been documented.

The return value from net:getaddrinfo/2 has been corrected: the protocol field is now an atom(), instead of, incorrectly, list(atom()). The documentation has also been corrected about this return type.

Deferred close of a socket:sendfile/* file was broken and has been corrected.

Some debug code, not enabled by default, in the socket NIF has been corrected to not accidentally core dump for debug printouts of more or less innocent events.

Own Id: OTP-17452

Dirty execution of a process in combination with an unlink signal from a port to the process could cause the signal queue of the process to enter into an inconsistent state. The result of the inconsistency typically caused a crash of the runtime system. This bug was introduced in OTP 23.3 (ERTS version 11.2).

Own Id: OTP-17462 Aux Id: GH-4885, PR-4914, OTP-17127

## Erts 12.0.1

### Fixed Bugs and Malfunctions

Commit of generated configure script.

Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

## Erts 12.0

### Fixed Bugs and Malfunctions

file:open/2 now throws an badarg error when opened with both the ram and raw options.

Own Id: OTP-16822 Aux Id: PR-2723

The estone benchmark has been updated to better reflect changes in the compiler and run-time system.

Own Id: OTP-16879

Fix profile guided optimization of run-time system when using GCC 7 or later.

Own Id: OTP-16880

Fix double close of fd when creating crash dump.

Own Id: OTP-16884

Improve erl error message when unable to open included args_file.

Own Id: OTP-17014

Remove warning text about the -- operation from documentation

The -- operation was optimized in Erlang/OTP 22 so that its worst case complexity is O(N*log(N)), where N is the total size of the input lists. Therefore, the warning in the documentation saying that the time complexity is proportional to length(A)*length(B) is incorrect and is no longer needed. Notice that Erlang/OTP 21 will no longer be supported when Erlang/OTP 24 gets released.

Own Id: OTP-17020

A floating point zero (0.0) can be both positive (+0.0) and negative (-0.0). Multiple bugs in the compiler, runtime system, and STDLIB have been fixed to ensure that the minus sign on 0.0 is not lost.

Own Id: OTP-17077 Aux Id: ERL-1431, PR-2903, PR-2905, PR-2906

Fix compiler warnings produced by the clang compiler.

Own Id: OTP-17105 Aux Id: PR-2872

Windows process erl.exe killed if its service process erlsrv.exe terminates.

Own Id: OTP-17131 Aux Id: PR-3031, GH-4360

The configure scripts in crypto and erts now fail if a requested feature cannot be enabled.

Large parts of the configure script of crypto have been rewritten with various improvements and bug fixes. It is now better at finding usable OpenSSL libraries, but will in the following cases fail to detect OpenSSL libraries where it previously sometimes detected the libraries by chance:

OpenSSL installations with include directory and lib directory parts installed in different base directories. In order to detect such installations after this change, the user must explicitly specify the locations using the --with-ssl=<path> and the --with-ssl-incl=<path> configure command line arguments. When building with old gcc compilers or other compilers on Debian derivatives with multiarch directories under the lib directory. In order to detect such installations after this change, the user must explicitly specify the multiarch directory name using the --with-ssl-lib-subdir=lib/<multiarch-dir> configure command line argument.

Own Id: OTP-17254 Aux Id: ERIERL-618, GH-4230

The erl command line arguments +Bi, +Bd, and +B erroneously caused reception of the USR1 signal to terminate the runtime system without creating a crash dump. Reception of the USR1 signal now always cause termination with creation of a crash dump, regardless of command line arguments passed. This bug has existed at least since OTP R5B.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-17275 Aux Id: PR-4553

Add check to make sure that when passing an option to erl that requires an argument, but none is given, we report an error. This fixes a bug introduced in OTP-22.1 via OTP-15926.

Own Id: OTP-17314 Aux Id: OTP-15926, GH-4624, PR-

The "Last calls" section in crash dumps have been updated to print newlines after each non-function save_calls state (send, receive, timeout).

Own Id: OTP-17329 Aux Id: PR-4730

Sockets created with socket:accept not counted (socket:info/0).

Own Id: OTP-17372

### Improvements and New Features

The experimental socket module can now use any protocol (by name) the OS supports. Suggested in PR-2641, implemented in PR-2670.

Own Id: OTP-14601 Aux Id: PR-2641, PR-2670, OTP-16749

New functions enif_dynamic_resource_call enables NIFs to call native code in another NIF module. The call is done via a resource callback function dyncall supplied by the user with the new enif_init_resource_type.

Own Id: OTP-14753

Runtime support for new improved selective receive optimization.

Own Id: OTP-16226 Aux Id: OTP-10391

The deprecated function erlang:get_stacktrace/0 has been removed. Use the new syntax in try/catch to retrieve the stack backtrace.

Own Id: OTP-16653

Support for handling abstract code created before OTP R15 has been dropped.

Own Id: OTP-16678 Aux Id: PR-2627

Extended error information for failing BIF calls as proposed in EEP 54 has been implemented.

When a BIF call from the Erlang shell fails, more information about which argument or arguments that were in error will be printed. The same extended error information will by proc_lib, common_test, and qlc when BIF calls fail.

For applications that wish to provide the same extended error information, there are new functions erl_error:format_exception/3 and erl_error:format_exception/4.

There is a new error/3 BIF that allows applications or libraries to provide extended error information in the same way for their own exceptions.

Own Id: OTP-16686

The erlang module documentation has been updated to improve clarity and description of edge cases.

Own Id: OTP-16687 Aux Id: PR-2996 PR-2762

An example implementation of Erlang distribution over UDS using distribution processes has been introduced.

Thanks to Jérôme de Bretagne

Own Id: OTP-16703 Aux Id: PR-2620

Improve code generation when creating funs by adding a new beam instruction make_fun3 that does not do GC and allows for better register allocation.

Own Id: OTP-16712

The process alias feature as outlined by EEP 53 has been introduced. It is introduced in order to provide a lightweight mechanism that can prevent late replies after timeout or connection loss. For more information, see EEP 53 and the documentation of the new alias/1 BIF and the new options to the monitor/3 BIF.

The call operation in the framework used by gen_server, gen_statem, and gen_event has been updated to utilize alias in order to prevent late responses. The gen_statem behavior still use a proxy process in the distributed case, since it has always prevented late replies and aliases wont work against pre OTP 24 nodes. The proxy process can be removed in OTP 26.

The alias feature also made it possible to introduce new functions similar to the erpc:receive_response() function in the gen behaviors, so the new functions gen_server:receive_response(), gen_statem:receive_response(), gen_event:receive_response() have also been introduced.

Own Id: OTP-16718 Aux Id: PR-2735

Accept 64-bit process identifiers from external nodes. This is the first step in an upgrade path toward using 64-bit pids in a future OTP release.

Own Id: OTP-16720 Aux Id: PR-2680

The experimental new socket API has been further developed. Some backwards incompatible changes with respect to OTP 23 have been made.

The control message format has been changed so a decoded value is now in the 'value' field instead of in the 'data' field. The 'data' field now always contains binary data.

Some type names have been changed regarding message headers and control message headers.

socket:bind/2 now returns plain ok instead of {ok, Port} which was only relevant for the inet and inet6 address families and often not interesting. To find out which port was chosen use socket:sockname/1.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16749 Aux Id: OTP-14601

Remove old unused +MYm and ERL_MALLOC_LIB options.

Own Id: OTP-16788

Increase timer resolution on windows.

Own Id: OTP-16814 Aux Id: PR-2704

The code loader has been rewritten in order to be able to load JIT:ed code. As a consequence of this, it is no longer possible to load HiPE code.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16878

Add support in the Erlang/OTP build system to generate a compilation database that can be used by third-party tools (such as irony in Emacs) to compile the erts C and C++ source code. Create the database using make compdb.

Own Id: OTP-16881

The BeamAsm JIT-compiler has been added to Erlang/OTP. The JIT-compiler is enabled by default on most x86 64-bit platforms that have a C++ compiler that can compile C++17. To verify that a JIT enabled emulator is running you can use erlang:system_info(emu_flavor).

For more information see the internal documentation of BeamAsm in erts.

Own Id: OTP-16885 Aux Id: PR-2745

By default all ERTS internal memory allocators based on alloc_util will now use their own separate carrier pool for migration of carriers instead of using a node global carrier pool. This was the default behavior between OTP 17 and OTP 21, but changed to use a node global carrier pool as of OTP 22.0. Usage of the node global carrier pool proved troublesome since it had a tendency to spread long lived blocks into allocators with normally short lived blocks causing increased memory fragmentation. The node global carrier pool behavior as well as other behaviors can be configured using the +M<S>cp command line argument.

Own Id: OTP-16898 Aux Id: OTP-16856

New functions have been added to the maps module: merge_with/3, intersect/2, intersect_with/3, filtermap/2, from_keys/2, and maps:foreach/2.

maps:merge_with/3 is the same as merge/2 but takes an extra fun that is used to combine items with the same key.

maps:intersect/2 computes the intersection of two maps.

maps:intersect_with/3 is the same as intersect/2 but takes an extra fun that is used to combine intersecting items.

maps:filtermap/2 allows filtering and mapping of a map in a single pass.

maps:from_keys/2 constructs a map from a list of keys and a single value and can be used to to optimize sets operations such as from_list/1, filter/2, intersection/2, and subtract/2.

maps:foreach/2 allows iteration over a map without returning any value.

Own Id: OTP-16936 Aux Id: ERL-1367

Change escripts to output any errors or warnings to standard error instead of standard out.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16945

A new erl parameter for specifying a file descriptor with configuration data has been added. This makes it possible to pass the parameter "-configfd FD" when executing the erl command. When this option is given, the system will try to read and parse configuration parameters from the file descriptor.

Own Id: OTP-16952

The experimental HiPE application has been removed, together with all related functionality in other applications.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16963

The pretty printer for floating point number have been changed to make it easier to see if the integer part of the number has been rounded. After the change the digit that may have been rounded always appears last or just before the exponent character (e or E). This is accomplished by always printing the number using scientific notation if it is so large that the integer part could be rounded.

Own Id: OTP-16980 Aux Id: ERL-1308

The erlang:monitor_node/2 BIF will now fail with a notalive exception if distribution has not been started on the current node; it used to fail with a badarg exception.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16987

Accept references up to a size of 160-bits from remote nodes. This is the first step in an upgrade path toward using references up to 160-bits in a future OTP release.

Own Id: OTP-17005 Aux Id: OTP-16718

Accept 64-bit port identifiers from external nodes. This is the first step in an upgrade path toward using 64-bit port identifiers in a future OTP release.

Own Id: OTP-17007

One can now pass the ERL_ROOTDIR environment variable to the erl and start scrips. This makes it easier to use Erlang for Android apps. On Android, apps don't control where they will be installed.

Own Id: OTP-17028

All long running functions in the maps API are now yielding. In previous releases the functions maps:from_list/1, maps:keys/1 and maps:values/1 did not yield. This could cause unfair scheduling of processes.

Own Id: OTP-17057

socket:sendfile/2,3,4,5 has been implemented, for platforms that support the underlying socket library call.

Own Id: OTP-17154 Aux Id: OTP-16749

The bit matching and construction syntax now supports 16-bit floats (IEEE 754-2008).

Own Id: OTP-17207

Add process_flag(fullsweep_after, N) to change fullsweep_after value in an already spawned process.

Own Id: OTP-17285 Aux Id: PR-4651

The max_heap_size error report has been updated to include the message queue size.

Own Id: OTP-17293 Aux Id: PR-4672

Introduce new types nonempty_binary() and nonempty_bitstring().

Own Id: OTP-17301 Aux Id: GH-4636

Optimize updates of large maps with identical keys and values. E.g. in the example below the original Map will be reused as the return of the second update.

1> Map = LargeMap#{ a => b }.

2> Map#{ a := b }.

The same optimization was done for small maps (< 33 keys) in erts-10.4 (OTP 22.0).

Own Id: OTP-17310 Aux Id: PR-4656

The previously undocumented internal -no_epmd option has been made documented and public.

Own Id: OTP-17341 Aux Id: PR-2945

Reduce memory carrier super alignment on 64-bit architectures. In practice allows more fine grained control over configuration of memory carrier sizes, from increments of 256kb to 16kb.

Own Id: OTP-17368

## Erts 11.2.2.10

### Fixed Bugs and Malfunctions

Fix GC emulator crash when spawn_request was used when message tracing was enabled.

Own Id: OTP-17871 Aux Id: PR-5612

## Erts 11.2.2.9

### Fixed Bugs and Malfunctions

Fixed a memory leak in file:read_file_info/2 and file:read_file/1 on Windows.

Own Id: OTP-17827 Aux Id: GH-5527

### Improvements and New Features

Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.

This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.

This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).

Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

## Erts 11.2.2.8

### Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.

Own Id: OTP-17735 Aux Id: GH-5339

Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:

EXIT signals with exit reasons of one word size. DOWN signals with exit reasons of one word size. demonitor signals from a terminating process. unlink_ack signals on OTP 23 and 24. spawn_reply signals on OTP 23 and 24.

Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

## Erts 11.2.2.7

### Fixed Bugs and Malfunctions

A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).

Own Id: OTP-17628

A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similiar race could also cause a memory leak when receiving an unlink signal.

Own Id: OTP-17642 Aux Id: PR-5248

The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.

On OTP 24 this could also cause the whole runtime system to crash.

Own Id: OTP-17651 Aux Id: GH-5235, PR-5244

Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.

Own Id: OTP-17665 Aux Id: PR-5248

This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.

Own Id: OTP-17677

Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.

The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.

Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.

Own Id: OTP-17700 Aux Id: GH-5271, PR-5273

### Improvements and New Features

The python scripts that existed in erts/lib_src/yielding_c_fun/lib/tiny_regex_c/scripts had a license that was incompatible with Erlang/OTP's license. This ticket removes these scripts that were not used by us.

Own Id: OTP-17658

## Erts 11.2.2.6

### Fixed Bugs and Malfunctions

Parsing of the result value in the native DNS resolver has been made more defensive against incorrect results.

Own Id: OTP-17578 Aux Id: ERIERL-683

On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17604

## Erts 11.2.2.5

### Fixed Bugs and Malfunctions

Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.

Own Id: OTP-17560 Aux Id: GH-5116

Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.

Own Id: OTP-17568 Aux Id: PR-4940

Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.

This bug has existed since Erlang/OTP 20.0.

Own Id: OTP-17585 Aux Id: GH-5150

binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17594

## Erts 11.2.2.4

### Fixed Bugs and Malfunctions

Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.

The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.

Own Id: OTP-17493

Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.

Own Id: OTP-17500 Aux Id: GH-4809

Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.

Own Id: OTP-17513 Aux Id: GH-4964, PR-5015

## Erts 11.2.2.3

### Fixed Bugs and Malfunctions

A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.

Own Id: OTP-17472 Aux Id: PR-4932

## Erts 11.2.2.2

### Fixed Bugs and Malfunctions

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).

Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

Dirty execution of a process in combination with an unlink signal from a port to the process could cause the signal queue of the process to enter into an inconsistent state. The result of the inconsistency typically caused a crash of the runtime system. This bug was introduced in OTP 23.3 (ERTS version 11.2).

Own Id: OTP-17462 Aux Id: GH-4885, PR-4914, OTP-17127

## Erts 11.2.2.1

### Fixed Bugs and Malfunctions

Commit of generated configure script.

Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

## Erts 11.2.2

### Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.

Own Id: OTP-17379 Aux Id: PR-4804

## Erts 11.2.1

### Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.

garbage-collect request. Sent from one process to another using one of the garbage_collect() BIFs. check-process-code request. Sent from one process to another using one of the check_process_code() BIFs. is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF. process-info reply. Sent as a response to a process calling one of the process_info() BIFs. port-command reply. Sent as a response to a process calling one of the port_command() BIFs. port-connect reply. Sent as a response to a process calling the port_connect() BIF. port-close reply. Sent as a response to a process calling the port_close() BIF. port-control reply. Sent as a response to a process calling the port_control() BIF. port-call reply. Sent as a response to a process calling the port_call() BIF. port-info reply. Sent as a response to a process calling one of the port_info() BIFs.

Own Id: OTP-17291

Fix bug in persistent_term:get/0 and info/0 that could cause VM crash in rare cases. Bug exists since OTP 23.0.

Own Id: OTP-17298

Fixed a bug in zlib where decompression would crash with data_error on some valid inputs.

Own Id: OTP-17299 Aux Id: GH-4710

A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.

Own Id: OTP-17307

A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.

Own Id: OTP-17349

## Erts 11.2

### Fixed Bugs and Malfunctions

Fix memory leak of about 6 words when erlang:process_flag/3 is called with a pid of an already dead process. Bug exists since OTP-21.0.

Own Id: OTP-17081 Aux Id: PR-2930

Fixed small memory leak in erl_drv_send_term and erl_drv_output_term when failing due to the term being invalid.

Own Id: OTP-17089 Aux Id: PR-2934

The DTrace/SystemTap process_heap_grow probe is now called with valid the heap and stack pointers for the process in question.

Own Id: OTP-17096 Aux Id: PR-2932

Fixed a performance issue in memory allocation for Linux kernels that didn't support MADV_FREE.

Own Id: OTP-17124

A new link protocol has been introduced which prevents links from ending up in an inconsistent state where one participant considers itself linked while the other doesn't. This bug has always existed in the distributed case, but has since OTP 21 also existed in the node local case since the distributed link protocol then was adopted also for node local links. The bug could, however, only trigger if both participants operated on the link simultaneously.

Own Id: OTP-17127

Fix memory leak when receiving sigchld from port program to already dead port.

Own Id: OTP-17163

Fix bug where complex seq_trace tokens (that is lists, tuples, maps etc) could becomes corrupted by the GC. The bug was introduced in OTP-21.

Own Id: OTP-17209 Aux Id: PR-3039

Fixed WSLPATH environment variable addition to PATH on windows, the last character was lost.

Own Id: OTP-17229

Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.

Own Id: OTP-17253

Fixed small memory leak in erlang:trace/3 if option {tracer,_} is included and the option list is invalid or the call races with a concurrent trace or code change operation.

Own Id: OTP-17265 Aux Id: PR-4596

Fix configure check for inet_pton on 32-bit windows. The failure of this check would cause epmd to be built without ipv6 support.

Own Id: OTP-17283

### Improvements and New Features

Various address sanitizer support.

Own Id: OTP-16959 Aux Id: PR-2965

The emulator will now honor cgroup2 CPU quotas.

Own Id: OTP-17002

Improved memory barrier usage on ARMv8 hardware, and specifically on Apple silicon.

Own Id: OTP-17195 Aux Id: PR-4505, PR-4538

Improved memory barrier usage on 64-bit POWER hardware.

Own Id: OTP-17200 Aux Id: PR-4510

Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.

Own Id: OTP-17244

Refinement of the documentation of the message_queue_data process flag.

Own Id: OTP-17252 Aux Id: PR-4568

## Erts 11.1.8

### Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:

Termination of a distribution controller process Disabling of the distribution on a node Gathering of memory allocator information using the instrument module Enabling, disabling, and gathering of msacc information Delivery of 'CHANGE' messages when time offset is monitored A call to erlang:cancel_timer() A call to erlang:read_timer() A call to erlang:statistics(io | garbage_collection | scheduler_wall_time) A call to ets:all() A call to erlang:memory() A call to erlang:system_info({allocator | allocator_sizes, _}) A call to erlang:trace_delivered()

The bug existed on runtime systems running on all types of hardware except for x86/x86_64.

Own Id: OTP-17185

## Erts 11.1.7

### Improvements and New Features

Make windows installer remove write access rights for non admin users when installing to a non default directory. Reduces the risk for DLL sideloading, but the user should always be aware of the access rights for the installation.

Own Id: OTP-17097

## Erts 11.1.6

### Fixed Bugs and Malfunctions

The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.

Own Id: OTP-17080

The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.

Own Id: OTP-17088 Aux Id: ERIERL-580

## Erts 11.1.5

### Fixed Bugs and Malfunctions

Fix emulator crash when sending small bit-strings over Erlang distribution while the connection is being setup.

The fault was introduced in OTP-23.0

Own Id: OTP-17083 Aux Id: ERIERL-572

## Erts 11.1.4

### Fixed Bugs and Malfunctions

Fixed bug which could cause VM crash when a NIF is loaded at the same time as the Erlang implementation of the NIF is called. Bug exists since OTP 23.0.

Own Id: OTP-16859

Fixed enif_make_map_* functions in debug build when given environment from enif_alloc_env.

Own Id: OTP-16863 Aux Id: ERL-1352

Fixed broken configuration option --disable-pie.

Own Id: OTP-16864

Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.

Own Id: OTP-16869 Aux Id: ERL-1337

Fixed a performance issue when extremely many items were stored in the process dictionary. (Fixing this bug also eliminates a compiler warning emitted by the latest version of Clang.)

Own Id: OTP-16888

Remove -ftree-copyrename from flags passed to compiler when building erts. The flag is not used by modern gcc's and is not supported by clang.

Own Id: OTP-16894

Modules using complicated nested binary comprehensions could fail to load.

Own Id: OTP-16899

Fixed a race in file:read_file/1 were an incomplete file could be returned if another OS process swapped the file out while reading.

Own Id: OTP-16948 Aux Id: PR-2792

The call list_to_integer("10", true) would return 4 instead of raising an exception. Certain other atoms would also be interpreted as a number base.

Own Id: OTP-17030

On macOS 11 (Big Sur), erl would not start if the maximum number of file descriptors were unlimited (ulimit -n unlimited).

Own Id: OTP-17055 Aux Id: ERL-1417

### Improvements and New Features

Add manifest to all executables and dynamic libraries.

Own Id: OTP-17067 Aux Id: PR-2907

## Erts 11.1.3

### Fixed Bugs and Malfunctions

Fixed a crash when exceptions were thrown during call time tracing.

Own Id: OTP-16994

## Erts 11.1.2

### Fixed Bugs and Malfunctions

Fixed bugs causing issues when enabling the ERTS internal allocators on a system built with the undocumented and unsupported SMALL_MEMORY feature.

Own Id: OTP-16939

The inet driver used to use 16 as maximum elements in an I/O vector passed to writev() (and WSASend() on Windows). When the data to send contained lots of elements, this caused a performance degradation since repeated calls to writev() had to be made to a much larger extent. The inet driver now looks up actual maximum amount of elements that can be used on the system, instead of just assuming 16. On most systems this will result in a maximum amount of I/O vector elements of 1024.

As of OTP 23.0 the term encoding of signals to send over the distribution are encoded into I/O vectors of buffers instead of into a single buffer. Reference counted binaries are referred to directly from the I/O vector instead of being copied into the single buffer. That is, Erlang signals containing huge amounts of reference counted binaries was effected by this performance degradation.

Own Id: OTP-16955 Aux Id: ERL-1343, OTP-15618

In the distributed case, a faulty reply option in a call to the spawn_request() BIF erroneously caused a badarg exception instead of a badopt error message reply.

Own Id: OTP-16991 Aux Id: OTP-15251

## Erts 11.1.1

### Fixed Bugs and Malfunctions

inet:setopts([{active,once}]) wakes up IO polling thread unnecessarily, leading to lock contention and visibly higher CPU utilization.

Own Id: OTP-16847 Aux Id: ERL-1301

Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.

Own Id: OTP-16870

Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.

Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763

When compiling Erlang/OTP on macOS using Xcode 12, the performance of the BEAM interpreter would be degraded.

Own Id: OTP-16892

### Improvements and New Features

As of OTP 22, the allocator specific memory carrier pools were replaced by a node global carrier pool. This unfortunately caused substantial memory fragmentation in some cases due to long lived data being spread into carriers used by allocators mainly handling short lived data.

A new command line argument +M<S>cp has been introduced with which one can enable the old behavior as well as configuring other behaviors for the carrier pools. In order to configure the old behavior, with allocator specific carrier pools for all allocators, pass +Mucp : (including the colon character) as a command line argument to erl when starting the Erlang system.

The default configuration for carrier pools will be changed to +Mucp : some time in the future, but not in this patch.

Own Id: OTP-16856

## Erts 11.1

### Fixed Bugs and Malfunctions

Update the documentation of the abstract format to use ANNO instead of LINE.

Own Id: OTP-16625 Aux Id: PR-2609

The emulator will no longer revert to the default number of schedulers when running under a CPU quota lower than 1 CPU.

Own Id: OTP-16710 Aux Id: ERL-1280

Fixed a problem with crash dumps. When a process that contained reference to literals internally created by the runtime system (such as the tuple returned by os:type/0), the literal would not be included in the crash dump and the crashdump viewer would complain about the heap being incomplete.

Own Id: OTP-16713

Fix configure detection of PGO for clang.

Own Id: OTP-16738

The to_erl program has been fixed to correctly interpret newline as only newline and not newline+return.

This bug would cause the terminal to behave strangely when using lines longer than the terminal size.

Own Id: OTP-16741

A race condition when changing process priority by calling process_flag(priority, Prio) could cause elevation of priority for a system task to be ignored. This bug hit if the system task was scheduled on the process calling process_flag() at the same time as the priority was changed. The bug is quite harmless and should hit very seldom if ever.

Own Id: OTP-16770

Adjust /bin/sh to /system/bin/sh in scripts when installing on Android.

Own Id: OTP-16833 Aux Id: PR-2729

In rare circumstances, when loading a BEAM file generated by an alternative code generator (not the Erlang compiler in OTP) or from handwritten or patched BEAM code, the loader could do an unsafe optimization.

Own Id: OTP-16850 Aux Id: ERL-1344

A memory and file descriptor leak in socket has been fixed. (When a newly opened socket that had not entered the fd into the VM's poll set (neither received, sent, accepted nor connected) was abandoned without closing (process died), after assigning a different controlling process, then a memory block and the file descriptor could be leaked.)

Own Id: OTP-16857

The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.

Own Id: OTP-16866 Aux Id: ERL-1355

### Improvements and New Features

Changes in order to build on the Haiku operating system.

Thanks to Calvin Buckley

Own Id: OTP-16707 Aux Id: PR-2638

When building the inet driver on Windows, there where many compiler warnings regarding type casting (used when calling the debug macro). This has now been resolved.

Own Id: OTP-16715

Make (use of) the socket registry optional (still enabled by default). Its now possible to build OTP with the socket registry turned off, turn it off by setting an environment variable and controlling in runtime (via function calls and arguments when creating sockets).

Own Id: OTP-16763

Change default filename encoding on android to UTF-8.

Own Id: OTP-16821 Aux Id: PR-2733

Clarification of the format of the atom cache header used by the distribution.

Own Id: OTP-16848 Aux Id: PR-2737

## Erts 11.0.4

### Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.

Own Id: OTP-16780 Aux Id: PR-2701

## Erts 11.0.3

### Fixed Bugs and Malfunctions

Fixed bug in erlang:load_nif/2 that could cause it to throw badarg exception if a concurrent code change operation was in progress. Bug existed since OTP 23.0.

Own Id: OTP-16704 Aux Id: ERL-1273, PR-16704

Minor fix of debug compiled VM.

Own Id: OTP-16717

An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.

Own Id: OTP-16766 Aux Id: ERL-1304

NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.

Own Id: OTP-16772 Aux Id: ERL-1304

## Erts 11.0.2

### Fixed Bugs and Malfunctions

Fixed bug when sending an export fun (eg lists:reverse/1) on a not yet established connection. It could cause VM crash. Bug exists since OTP 23.0.

Own Id: OTP-16693 Aux Id: ERL-1254, PR-2640

## Erts 11.0.1

### Fixed Bugs and Malfunctions

The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.

The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.

Own Id: OTP-16639 Aux Id: ERL-1236

SCTP and UDP recv/2,3 hangs indefinitely if socket is closed while recv is called (socket in passive mode).

Own Id: OTP-16654 Aux Id: ERL-1242

## Erts 11.0

### Fixed Bugs and Malfunctions

BIFs now behave like ordinary functions with regard to tracing, allowing call_count tracing and fixing a few bugs where return trace messages were lost when BIFs tail-called themselves or other functions ("trapping").

Own Id: OTP-14734 Aux Id: ERL-496

Fix various compiler warnings on 64-bit Windows.

Own Id: OTP-15800

erlang:fun_info(fun foo/1, name/1) used to return a function name based on the name of the function that fun foo/1 was used in. The name returned is now -fun.foo/1-.

Own Id: OTP-15837

file:allocate/3 will now update the file size on all platforms.

Own Id: OTP-16155 Aux Id: PR-2408

erlang:decode_packet with type set to httph no longer accepts http headers that have whitespaces in between the header name and the colon. That is:

Content-Type : text/html

is no longer allowed. This has been changed to conform with RFC 7230 and thus protect against http desync attacks.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16168 Aux Id: ERL-1053

Fix the quoting rules in erl -args_file, ERL_FLAGS, ERL_AFLAGS and ERL_ZFLAGS to work as unix sh quoting.

This bug fix can make previous configuration options to erl passed through ERL_FLAGS, ERL_AFLAGS, ERL_ZFLAGS or -args_file not be interpreted in the same way as before the fix.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16244 Aux Id: ERL-1051

Fix the Erlang distribution to handle the scenario when a node connects that can handle message fragmentation but can not handle the atom cache. This bug only affects users that have implemented a custom distribution carrier. It has been present since OTP-21.

The DFLAG_FRAGMENT distribution flag was added to the set of flags that can be rejected by a distribution implementation.

Own Id: OTP-16284

Compiling a match specification with excessive nesting caused the runtime system to crash due to scheduler stack exhaustion. Instead of crashing the runtime system, effected functions will now raise a system_limit error exception in this situation.

Own Id: OTP-16431 Aux Id: ERL-592

Fixed a bug that prevented Erlang from being started on Windows if it were installed on certain paths.

Own Id: OTP-16478 Aux Id: ERL-1115

Fix bug on Windows causing bad performance when standard input is closed, especially if the VM is only assigned one CPU core. Could be provoked for example by starting erl or escript via function os:cmd/1. Could be avoided with command line option -noinput.

The bad performance was caused by an io thread spinning indefinitely.

Own Id: OTP-16521 Aux Id: ERL-716

Fixed a bug on Unix platforms that would cause file:read_file_info/1 to return incorrect results if the emulator's effective user or group id differed from its actual ones.

Own Id: OTP-16571

socket: Compile problems on Android when PACKET_FASTROUTE and PACKET_USER are both defined and has the same value. Use of PACKET_FASTROUTE has been removed as it may be unused and also only for none user-land.

Own Id: OTP-16576 Aux Id: ERL-1208

Fixed bug in erl_crash.dump generation that could cause a SEGV core dump if a recently cancelled timer was found.

Own Id: OTP-16596 Aux Id: ERL-1105, PR-2606

### Improvements and New Features

Improved concurrency of erlang:load_nif/2 as it does no longer block other schedulers from executing during initial load of a NIF library.

Own Id: OTP-10278

EEP-52 has been implemented.

In binary matching, the size of the segment to be matched is now allowed to be a guard expression, and similarly in map matching the keys can now be guard expressions. See the Erlang Reference Manual and Programming Examples for more details.

Language compilers or code generators that generate Core Erlang code may need to be updated to be compatible with the compiler in OTP 23. For more details, see the section Backwards Compatibility in EEP 52.

Own Id: OTP-14708

Internally in BEAM, handling of continuation pointers has been simplified. This change is not user-visible, except when examing a process stack in the crashdump viewer. The continuation pointer for a function will now be stored below the y(0) for that function.

Own Id: OTP-15077

seq_trace tokens are now propagated to spawned processes.

Own Id: OTP-15232 Aux Id: ERL-700

Improvements of distributed spawn operations. These include both scalability and performance improvements as well as new functionality.

New functionality:

A distributed spawn_monitor() BIF.

Support for monitor option in the distributed spawn_opt() BIF.

New spawn_request() BIFs for asynchronous spawn of processes. spawn_request() supports all options that spawn_opt() support plus a few more.

Own Id: OTP-15251

Make ets:insert/2 and ets:insert_new/2 yield scheduler execution on long lists of records to insert.

Own Id: OTP-15517 Aux Id: ERL-560

Increased size of node incarnation numbers (aka "creation"), from 2 bits to 32 bits. This will reduce the risk of pids/ports/refs, from different node incarnation with the same name, being mixed up.

Own Id: OTP-15603

The runtime system can now encode Erlang terms to the Erlang external term format as I/O vectors. The main benefit of this is that reference counted binaries can be referred to directly instead of copied into a new binary.

The default Erlang distribution over TCP will always utilize this. Alternate distribution implementations utilizing a port as distribution controller will utilize this if the driver implements the outputv callback. Alternate Erlang distribution implementations utilizing a process as distribution controller will utilize this if I/O vectors are utilized by the functionality that processes the data returned from erlang:dist_ctrl_get_data().

The return type for data returned by erlang:dist_ctrl_get_data() has been changed from iodata() to iovec(). Note that iovec() data is valid iodata() so old implementations using erlang:dist_ctrl_get_data() do not need to be changed, but may benefit from being changed depending on usage scenario.

The new BIFs term_to_iovec/1 and term_to_iovec/2 have been introduced. These work exactly as term_to_binary() with the corresponding arity except the return type.

Own Id: OTP-15618

Improved ETS scalability of concurrent calls that change the size of a table, like ets:insert/2 and ets:delete/2.

This performance feature was implemented for ordered_set in OTP 22.0 and does now apply for all ETS table types.

The improved scalability may come at the cost of longer latency of ets:info(T,size) and ets:info(T,memory). A new table option decentralized_counters has therefore been added. It is default true for ordered_set with write_concurrency enabled and default false for all other table types.

Own Id: OTP-15744 Aux Id: OTP-15623, PR-2229

Directories can now be opened by file:open/2 when passing the directory option.

Own Id: OTP-15835 Aux Id: PR-2212

Add Hygon Dhyana as known processor to enable support for atomic operations.

Own Id: OTP-15840

Make erlang:phash2 functions consume reductions proportional to the size of the input term and yield scheduler when reductions are depleted.

Own Id: OTP-15842 Aux Id: PR-2182

Fix various build issues when compiling Erlang/OTP to the IBM AIX platform.

Own Id: OTP-15866 Aux Id: PR-2110

Add configure options --enable-pie and --disable-pie to control the build of position independent executables.

Own Id: OTP-15868

file:read_file_info/2 can now be used on opened files and directories.

Own Id: OTP-15956 Aux Id: PR-2231

Add arity-1 versions of atom_to_binary, binary_to_atom and binary_to_existing_atom, all with utf8 as default encoding.

Own Id: OTP-15995 Aux Id: PR-2358

Optimized the erts internal hash table implementation for faster lookups. The internal hash is used for things like; the process registry, executing erlang:apply/2, executing M:func(test), and more.

Own Id: OTP-16014 Aux Id: PR-2345

CPU quotas are now taken into account when deciding the default number of online schedulers, improving performance in container environments where quotas are applied, such as docker with the --cpus flag.

Own Id: OTP-16105 Aux Id: ERL-927

The -config option to erl now can take multiple config files without repeating the -config option. Example:

erl -config sys local

Own Id: OTP-16148 Aux Id: PR-2373

Removed the scheduler_poll and async I/O dtrace and LTTng trace probes.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16215

Optimized persistent_term:put/2 and erase/1 to consume less CPU in many cases.

Own Id: OTP-16237 Aux Id: PR-2389

The possibility to run Erlang distribution without relying on EPMD has been extended. To achieve this a couple of new options to the inet distribution has been added.

-dist_listen false Setup the distribution channel, but do not listen for incoming connection. This is useful when you want to use the current node to interact with another node on the same machine without it joining the entire cluster. -erl_epmd_port Port Configure a default port that the built-in EPMD client should return. This allows the local node to know the port to connect to for any other node in the cluster.

The erl_epmd callback API has also been extended to allow returning -1 as the creation which means that a random creation will be created by the node.

In addition a new callback function called listen_port_please has been added that allows the callback to return which listen port the distribution should use. This can be used instead of inet_dist_listen_min/max if the listen port is to be fetched from an external service.

Own Id: OTP-16250

On systems without closefrom(), such as Linux, iterating over all possible file descriptors and calling close() for each is inefficient. This is markedly so when the maximum number of file descriptors has been tuned to a large number.

Instead, in erl_child_setup, walk the open descriptors under /dev/fd and close only those which are open.

This optimization affects the CPU usage of starting a new Erlang instance.

Own Id: OTP-16270

Optimized maps:merge/2 for trivial cases of an empty map(s) or same map.

Own Id: OTP-16283 Aux Id: PR-2441

The new experimental socket module has been moved to the Kernel application.

Own Id: OTP-16312

Improved the presentation of allocations and carriers in the instrument module.

Own Id: OTP-16327

As announced in OTP 22.0, the previously existing limited support for VxWorks has now been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16329 Aux Id: OTP-15621

The return value when using the httph and httph_bin option to erlang:decode_packet/3 and inet:setopts/2 has been changed to also include the original header unmodified. See erlang:decode_packet/3. Example:

     >
    	    erlang:decode_packet(httph_bin,<<"HELLO:
    	    hi\r\n\r\n">>,[]).
    	    {ok,{http_header,0,<<"Hello">>,<<"HELLO">>,<<"hi">>},<<"\r\n">>}

Own Id: OTP-16347 Aux Id: PR-2466

Ensure net_kernel:monitor_nodes/1 sends nodedown messages of a failed connection before nodeup messages of a reestablished connection toward the same node.

Own Id: OTP-16362

Update of sequential tracing to also support other information transfers than message passing.

Own Id: OTP-16370 Aux Id: OTP-15251, OTP-15232

socket: It is now possible to create a socket from an already existing file descriptor.

Own Id: OTP-16398 Aux Id: ERL-1154

socket: The socket:supports/1 function now also report if netns is supported or not.

Own Id: OTP-16432

=:= has been optimized to return false immediately when comparing two maps of different sizes.

Own Id: OTP-16454

Changed the behaviour of passing the erl command line argument +A 0 to silently imply +A 1. That is, it will no longer be possible to completely disable the async thread pool. Disabling of the async thread pool has since OTP 21 had no benefits; only lots of drawbacks.

Own Id: OTP-16482

The deprecated erlang:get_stacktrace/0 BIF now returns an empty list instead of a stacktrace. To retrieve the stacktrace, use the extended try/catch syntax that was introduced in OTP 21. erlang:get_stacktrace/0 is scheduled for removal in OTP 24.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-16484

init:restart/1 has been introduced. init:restart/1 can be utilized for changing the code loading mode during a restart.

Own Id: OTP-16492 Aux Id: PR-2461

Improve configure for the net nif, which should increase portability.

Own Id: OTP-16530 Aux Id: OTP-16464

socket: Socket counters and socket global counters are now represented as maps (instead of property lists).

Own Id: OTP-16535

Reduced the resource usage of erlc in parallel builds (e.g. make -j128).

Own Id: OTP-16543 Aux Id: ERL-1186

The experimental socket module has gotten restrictions removed so now the 'seqpacket' socket type should work for any communication domain (protocol family) where the OS supports it, typically the Unix Domain.

Own Id: OTP-16550 Aux Id: ERIERL-476

Updated the internal pcre library to 8.44.

Own Id: OTP-16557

There is now cost in terms of reductions when copying binary data using the binary syntax.

Own Id: OTP-16601 Aux Id: OTP-16577

The executable erl_call is now part of the erts distribution in addition to erl_interface.

Own Id: OTP-16602

Fix a buffer overflow bug that caused EPMD to consume 100% CPU after many nodes had been connected on the same time on NetBSD.

Own Id: OTP-16615

erl -remsh now uses the dynamic node names feature by default. See the erl documentation for details.

Own Id: OTP-16616

socket: By default the socket options rcvtimeo and sndtimeo are now disabled. To enable these, OTP now has to be built with the configure option --enable-esock-rcvsndtimeo

Own Id: OTP-16620

The environment variable $HOME does no longer have to be set before Erlang can be started.

Own Id: OTP-16635 Aux Id: ERL-476 PR-2390

## Erts 10.7.2.16

### Improvements and New Features

Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.

This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.

This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).

Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

## Erts 10.7.2.15

### Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.

Own Id: OTP-17735 Aux Id: GH-5339

Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:

EXIT signals with exit reasons of one word size. DOWN signals with exit reasons of one word size. demonitor signals from a terminating process. unlink_ack signals on OTP 23 and 24. spawn_reply signals on OTP 23 and 24.

Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

## Erts 10.7.2.14

### Fixed Bugs and Malfunctions

On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17604

A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).

Own Id: OTP-17628

A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similiar race could also cause a memory leak when receiving an unlink signal.

Own Id: OTP-17642 Aux Id: PR-5248

The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.

On OTP 24 this could also cause the whole runtime system to crash.

Own Id: OTP-17651 Aux Id: GH-5235, PR-5244

Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.

Own Id: OTP-17665 Aux Id: PR-5248

This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.

Own Id: OTP-17677

Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.

The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.

Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.

Own Id: OTP-17700 Aux Id: GH-5271, PR-5273

## Erts 10.7.2.13

### Fixed Bugs and Malfunctions

Fixed a bug in zlib where decompression would crash with data_error on some valid inputs. The bug could also cause extraction from a zip archive using zip:extract() to fail.

Own Id: OTP-17470 Aux Id: ERIERL-657

A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.

Own Id: OTP-17472 Aux Id: PR-4932

Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.

The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.

Own Id: OTP-17493

Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.

Own Id: OTP-17500 Aux Id: GH-4809

Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.

Own Id: OTP-17513 Aux Id: GH-4964, PR-5015

Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.

Own Id: OTP-17560 Aux Id: GH-5116

Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.

Own Id: OTP-17568 Aux Id: PR-4940

Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.

This bug has existed since Erlang/OTP 20.0.

Own Id: OTP-17585 Aux Id: GH-5150

binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.

Own Id: OTP-17594

## Erts 10.7.2.12

### Fixed Bugs and Malfunctions

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).

Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

## Erts 10.7.2.11

### Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.

Own Id: OTP-17379 Aux Id: PR-4804

Commit of generated configure script.

Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

## Erts 10.7.2.10

### Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.

garbage-collect request. Sent from one process to another using one of the garbage_collect() BIFs. check-process-code request. Sent from one process to another using one of the check_process_code() BIFs. is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF. process-info reply. Sent as a response to a process calling one of the process_info() BIFs. port-command reply. Sent as a response to a process calling one of the port_command() BIFs. port-connect reply. Sent as a response to a process calling the port_connect() BIF. port-close reply. Sent as a response to a process calling the port_close() BIF. port-control reply. Sent as a response to a process calling the port_control() BIF. port-call reply. Sent as a response to a process calling the port_call() BIF. port-info reply. Sent as a response to a process calling one of the port_info() BIFs.

Own Id: OTP-17291

A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.

Own Id: OTP-17307

A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.

Own Id: OTP-17349

## Erts 10.7.2.9

### Fixed Bugs and Malfunctions

Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.

Own Id: OTP-17253

Fix bug in call_time tracing (used by eprof) that could cause VM crash. Bug exists since OTP-22.2 (but not in OTP-23).

Own Id: OTP-17290 Aux Id: GH-4635

### Improvements and New Features

Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.

Own Id: OTP-17244

## Erts 10.7.2.8

### Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:

Termination of a distribution controller process Disabling of the distribution on a node Gathering of memory allocator information using the instrument module Enabling, disabling, and gathering of msacc information Delivery of 'CHANGE' messages when time offset is monitored A call to erlang:cancel_timer() A call to erlang:read_timer() A call to erlang:statistics(io | garbage_collection | scheduler_wall_time) A call to ets:all() A call to erlang:memory() A call to erlang:system_info({allocator | allocator_sizes, _}) A call to erlang:trace_delivered()

The bug existed on runtime systems running on all types of hardware except for x86/x86_64.

Own Id: OTP-17185

## Erts 10.7.2.7

### Fixed Bugs and Malfunctions

The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.

Own Id: OTP-17080

The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.

Own Id: OTP-17088 Aux Id: ERIERL-580

## Erts 10.7.2.6

### Fixed Bugs and Malfunctions

Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.

Own Id: OTP-16869 Aux Id: ERL-1337

## Erts 10.7.2.5

### Fixed Bugs and Malfunctions

Fixed bugs causing issues when enabling the ERTS internal allocators on a system built with the undocumented and unsupported SMALL_MEMORY feature.

Own Id: OTP-16939

## Erts 10.7.2.4

### Fixed Bugs and Malfunctions

inet:setopts([{active,once}]) wakes up IO polling thread unnecessarily, leading to lock contention and visibly higher CPU utilization.

Own Id: OTP-16847 Aux Id: ERL-1301

The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.

Own Id: OTP-16866 Aux Id: ERL-1355

Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.

Own Id: OTP-16870

Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.

Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763

### Improvements and New Features

As of OTP 22, the allocator specific memory carrier pools were replaced by a node global carrier pool. This unfortunately caused substantial memory fragmentation in some cases due to long lived data being spread into carriers used by allocators mainly handling short lived data.

A new command line argument +M<S>cp has been introduced with which one can enable the old behavior as well as configuring other behaviors for the carrier pools. In order to configure the old behavior, with allocator specific carrier pools for all allocators, pass +Mucp : (including the colon character) as a command line argument to erl when starting the Erlang system.

The default configuration for carrier pools will be changed to +Mucp : some time in the future, but not in this patch.

Own Id: OTP-16856

## Erts 10.7.2.3

### Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.

Own Id: OTP-16780 Aux Id: PR-2701

## Erts 10.7.2.2

### Fixed Bugs and Malfunctions

An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.

Own Id: OTP-16766 Aux Id: ERL-1304

NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.

Own Id: OTP-16772 Aux Id: ERL-1304

## Erts 10.7.2.1

### Fixed Bugs and Malfunctions

Fixed bug in erl_crash.dump generation that could cause a SEGV core dump if a recently cancelled timer was found.

Own Id: OTP-16596 Aux Id: ERL-1105, PR-2606

The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.

The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.

Own Id: OTP-16639 Aux Id: ERL-1236

SCTP and UDP recv/2,3 hangs indefinitely if socket is closed while recv is called (socket in passive mode).

Own Id: OTP-16654 Aux Id: ERL-1242

## Erts 10.7.2

### Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.

Own Id: OTP-16640 Aux Id: OTP-16193

The VM could potentially crash when checking process code of a process that terminated while executing a dirty NIF. The checking of process code is part of a code purge operation.

Own Id: OTP-16641

System tasks of low priority were not interleaved with normal priority system tasks as they should. This could potentially delay garbage collection of another process longer than intended if the garbage collection was requested from a low priority process.

Own Id: OTP-16642

## Erts 10.7.1

### Fixed Bugs and Malfunctions

re:run(Subject, RE, [unicode]) returned nomatch instead of failing with a badarg error exception when Subject contained illegal utf8 and RE was passed as a binary. This has been corrected along with corrections of reduction counting in re:run() error cases.

Own Id: OTP-16553

Fixed a bug that could cause the emulator to crash when purging modules or persistent terms.

Own Id: OTP-16555 Aux Id: ERL-1188

Fixed a bug in a receive optimization. This could cause a receive not to match even though a matching message was present in the message queue. This bug was introduced in ERTS version 10.6 (OTP 22.2).

Own Id: OTP-16572 Aux Id: ERL-1199, OTP-16269

## Erts 10.7

### Fixed Bugs and Malfunctions

gen_udp:recv(S, N, 0) corrupted the internal state for the socket so after receive with {active, once} it always returned {error, timeout}, and wasted the received UDP packets. This bug has now been fixed.

Reported and pinpointed by Alexander Petrovsky.

Own Id: OTP-16059

The atom esock_atom_user and esock_atom_kernel was never actually created. This has now been corrected.

Own Id: OTP-16381

Fixed bug in socket module that could potentially lead to scheduler deadlocks.

Own Id: OTP-16384

Fix bug causing VM crash if down or stop callback of a NIF resource is called after the NIF module has been purged. The fix will postpone unloading until all such resource objects have been garbage collected.

Own Id: OTP-16399

Fixed bug in ets:update_counter/4, when called with an invalid UpdateOp and a Key that does not exist, causing ets:info(T,size) to return incorrect values. Bug exists since OTP-19.0.2.

Own Id: OTP-16404 Aux Id: ERL-1127

Fix potential heap corrupting bugs when a process calls a BIF that blocks other normal schedulers and then writes to its own heap without the main process lock. A NIF running on a dirty scheduler trying to interact with such a process could corrupt its heap. The fixed BIFs were related to code loading and tracing.

Own Id: OTP-16417

Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.

Own Id: OTP-16438

The prim_net nif (net/kernel) made use of an undefined atom, notsup. This has now been corrected.

Own Id: OTP-16440

Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.

Own Id: OTP-16481

Fix a crash when attempting to log faults when loading files during early boot.

Own Id: OTP-16491

### Improvements and New Features

For socket, not all send and receive flags are supported on all platforms. In order to (at least) simplify testing, the socket:supports/0,1,2,3 functions has been extended with send_flags and recv_flags items, which indicates what the current platform can manage.

Own Id: OTP-16153

Add a "full featured" version of getifaddrs in the net module.

Own Id: OTP-16212 Aux Id: ERL-1070

The options busy_limits_port and busy_limits_msgq have been added to the BIF erlang:open_port/2. The busy_limits_port option can be used for controlling the busy state of a port executing the spawn_driver or the fd_driver. The busy_limits_msgq option can be used for controlling the busy state of the port message queue.

Own Id: OTP-16306 Aux Id: ERIERL-439

A socket "registry" has been added making it possible to list current open sockets.

Own Id: OTP-16309

The counters managed by the socket nif has been extended. Their "size" has been increased from 32 bit to 64. Two max package size (for read and write) has been added. And four accept counters has been added.

Own Id: OTP-16387

Add gcc option -fno-common to detect accidental name clashes of global variables.

Own Id: OTP-16420 Aux Id: PR-2513

New dynamic lock checker that verifies locking orders and detects potential deadlock bugs in drivers and NIFs. Enabled together with the old static lock checker (for ERTS internal locks) in emulator started with -emu_type debug or built with configuration option --enable-lock-checking.

Own Id: OTP-16427

## Erts 10.6.4

### Fixed Bugs and Malfunctions

A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.

Own Id: OTP-16446 Aux Id: ERL-1157

## Erts 10.6.3

### Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.

Own Id: OTP-16436 Aux Id: ERL-1152

### Improvements and New Features

Improved signal handling for processes executing dirty. For example, avoid busy wait in dirty signal handler process when process is doing garbage collection on dirty scheduler.

Own Id: OTP-16358

## Erts 10.6.2

### Fixed Bugs and Malfunctions

Taking a scheduler offline could cause timers set while executing on that scheduler to be delayed until the scheduler was put online again. This bug was introduced in ERTS version 10.0 (OTP 21.0).

Own Id: OTP-16371

The ets:update_counter/4 core dumped when given an ordered_set with write_concurrency enabled and an invalid position. This bug has been fixed.

Own Id: OTP-16378 Aux Id: ERL-1125

A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.

Own Id: OTP-16379

### Improvements and New Features

Duplicate entries for [socket:]getopt and [socket:]setopt in man page.

Own Id: OTP-16333 Aux Id: ERL-1104

## Erts 10.6.1

### Fixed Bugs and Malfunctions

Corrected an issue with the new socket api which could cause a core dump. A race during socket close could cause a core dump (an invalid nif environment free).

Own Id: OTP-16314 Aux Id: ERL-1098

Corrected an issue with the new socket api which could cause a core dump. When multiple accept processes waiting for a connect a connect could cause a core dump.

Own Id: OTP-16359

## Erts 10.6

### Fixed Bugs and Malfunctions

The functions unicode:characters_to_list() and unicode:characters_to_binary() raised a badarg exception instead of returning an error tuple when passed very large invalid code points as input.

Own Id: OTP-16052

file:allocate/3 will now work properly on Mac OS.

Own Id: OTP-16074 Aux Id: ERL-1042, PR-2386

For socket, invalid encoding of send and receive flags caused badarg and send failure.

Own Id: OTP-16149

Fix a bug in re on platforms where the native stack grows upwards, for instance on HP PA-RISC.

Own Id: OTP-16150 Aux Id: ERL-1043

For socket, unable to properly decode the timestamp control message header on FreeBSD. We incorrectly used the SO_TIMESTAMP flag for the timestamp control message header type. It should have been SCM_TIMESTAMP. This caused the timestamp control message header to not be fully decoded.

Own Id: OTP-16151 Aux Id: #2400

For socket, when setting the ip option 'recvtos' to true, thereby indicating that we want to receive the TOS control message header, we don't actually get TOS but RECVTOS on FreeBSD (and maybe others)! This was previously not handled.

Own Id: OTP-16152 Aux Id: OTP-16114

Fixed a bug where the emulator would print out error messages forever if it crashed during startup.

Own Id: OTP-16159 Aux Id: ERL-1060

For socket, wrong type for protocol caused segmentation fault if protocol was provided as {raw, integer()}.

Own Id: OTP-16163 Aux Id: ERL-1061

For socket, when setting the ip option 'recvttl' to true, thereby indicating that we want to receive the TTL control message header, we don't actually get TTL but RECVTTL on Solaris (and maybe others)! This was previously not handled.

Own Id: OTP-16172 Aux Id: OTP-16114

For socket, IPv6 control message headers was incorrectly decoded with level ip instead of ipv6.

Own Id: OTP-16173

Fix configure bug where clock_getres would not correctly be detected causing erlang:system_info(os_system_time_source) to return an incorrect resolution.

This bug effects all OSs that use clock_gettime to get time (basically all OSs except windows) and has been present since OTP-19.2.

Own Id: OTP-16191 Aux Id: ERL-1067

Fix bugs when using ERLC_USE_SERVER=true on Windows when building Erlang/OTP.

Change the cookie used by the compile server to be hard coded instead of using the users cookie.

Own Id: OTP-16192

Fix so that persistent_term is listed in the erts application file.

Own Id: OTP-16194

Fix bug in call_time tracing which could sometimes cause call time measurements being attributed to the wrong function.

Own Id: OTP-16195 Aux Id: ERL-1027

The socket socket option 'peek_off' has been disabled. If peek_off was set and then socket:recv/3 was called with the peek flag, the call could hang.

Own Id: OTP-16196

Handle possibly uninitiated (control message header) data.

Own Id: OTP-16197

For net, a couple of NI macros was deprecated in new versions of glibc, so these are no longer used (IDN_ALLOW_UNASSIGNED and IDN_USE_STD3_ASCII_RULES).

Own Id: OTP-16203

The string value from a get operation needed to be truncated.

Own Id: OTP-16204

Fix misleading seq_trace message for remote send operation toward named process. Changed receiver to be {Name,Node} instead of just Name.

Own Id: OTP-16206 Aux Id: PR-2423

Fixed a bug causing actual nodedown reason reported by net_kernel:monitor_nodes(true, [nodedown_reason]) to be lost and replaced by the reason killed.

Own Id: OTP-16216

For socket, the timestamp creation used when printing warning messages and debug printouts did not work. The used buffer was too small.

Own Id: OTP-16223

Fix compiler warnings generated by GCC 8

Own Id: OTP-16235

Fix erl -emu_type to accept the option opt which means the normal optimized emulator. This can be used to override the -emu_type option from environment variables.

Own Id: OTP-16297

Corrected the function spec to reflect the actual code of the function socket:bind.

Own Id: OTP-16310 Aux Id: ERL-1082

Fixed a performance issue in ETS lookup when using the compressed option and the term contained atoms. Before this fix the decompress algorithm for atoms would unnecessarily take a global lock to validate the atom.

Own Id: OTP-16316

### Improvements and New Features

For socket, not all send and receive flags are supported on all platforms. In order to (at least) simplify testing, the socket:supports/0,1,2,3 functions has been extended with send_flags and recv_flags items, which indicates what the current platform can manage.

Own Id: OTP-16153

For socket, add support for IPv6 socket options tclass and recvtclass. Both has been added, but the use of them are platform dependent. Call socket:supports(options, ipv6, Opt) to be sure what option to use in order to request a TCLASS control message header.

Own Id: OTP-16180

For socket, the TCP socket option cork was not supported even though the supports function reported it as such.

Own Id: OTP-16205

The Kernel application's User's Guide now contain a Logger Cookbook with with common usage patterns.

Own Id: OTP-16208

Add a "full featured" version of getifaddrs in the net module.

Own Id: OTP-16212 Aux Id: ERL-1070

Fix an inefficiency introduced by the bug fix in OTP-16241 which fixed a problem with the receive optimization. That bug fix introduced an inefficiency when using the receive optimization and a burst of messages arrive at once when the receiving process' mailbox was empty.

Own Id: OTP-16269 Aux Id: OTP-16241

For socket, added support for the socket option extended_err. Andreas Schultz.

Own Id: OTP-16302 Aux Id: #2449

ETS tables have been optimized to not use any locks when running in a system with only one scheduler enabled. This can provide significant performance gains for applications that use ETS tables heavily.

Own Id: OTP-16315

## Erts 10.5.6

### Fixed Bugs and Malfunctions

Large amounts of quickly executed dirty work could cause heavy contention on an internal spin lock. The spin lock was replaced by a mutex which behaves much better under these conditions.

Own Id: OTP-16301 Aux Id: ERL-1079

## Erts 10.5.5

### Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.

Own Id: OTP-16193

Fix bug causing VM crash due to memory corruption of distribution entry. Probability of crash increases if Erlang distribution is frequently disconnected and reestablished towards same node names. Bug exists since OTP-21.0.

Own Id: OTP-16224 Aux Id: ERL-1044

Fixed bug causing crash of VM built with configuration --enable--sharing-preserving. Provoked when a sent message contains both a bit string and the heap binary (< 65 bytes) which the bit string was matched from. Bug exists since OTP-19.0 but has seen to be easier to provoke since OTP-22.1.

Own Id: OTP-16265 Aux Id: ERL-1064

## Erts 10.5.4

### Fixed Bugs and Malfunctions

The compiler could do an unsafe optimization of receives, which would cause a receive to only scan part of the message queue.

This bug fix in the compiler fixes a bug in the socket module.

Own Id: OTP-16219 Aux Id: ERL-1076

Fix bug where the receive marker used by the runtime to do the receive queue optimization could be incorrectly set. The symptom of this would be that a message that should match in a receive never matches.

The bug requires the OTP-22 compiler and multiple selective receives to trigger. See OTP-16219 for details about the bug fix in the compiler.

Own Id: OTP-16241 Aux Id: ERL-1076 OTP-16219

## Erts 10.5.3

### Fixed Bugs and Malfunctions

Erlang/OTP can now be built on macOS Catalina (10.15).

Own Id: OTP-16177 Aux Id: ERL-1063

## Erts 10.5.2

### Improvements and New Features

Added the environment variable ERLC_SERVER_ID, which allows multiple compile servers to run separately under the same user.

Own Id: OTP-16125 Aux Id: ERIERL-412

## Erts 10.5.1

### Fixed Bugs and Malfunctions

A terminating process sending distributed 'EXIT' or 'DOWN' signals while terminating could end up in a state where no progress at all was made. This was triggered by a distribution channel that the terminating process was sending on got busy. This bug has existed since ERTS version 10.4 (OTP 22.0).

Own Id: OTP-16069

When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.

Own Id: OTP-16107 Aux Id: ERL-1049

## Erts 10.5

### Fixed Bugs and Malfunctions

If you set {linger,{true,0}} on a gen_tcp listen socket, accept a connection on that socket, and then close the accepted socket, now the linger zero setting is transferred to the accepted socket. Before this correction that information was lost and the close behaviour on the accepted socket incorrect.

Own Id: OTP-15370 Aux Id: ERIERL-353

Sending ancillary data implemented in OTP-15747 accidentally left behind test code that caused all UDP sends to fail on Windows. This has now been fixed.

Own Id: OTP-15422 Aux Id: OTP-15747

In the socket nif, used invalid flags when if-def'ing for supported TCP flags: TCP_MAXSEG and TCP_NODELAY (the support function).

Own Id: OTP-15827

Fixed memory leaks in experimental socket module.

Own Id: OTP-15830

re:run() now yields when validating utf8 in a large subject.

Own Id: OTP-15836 Aux Id: ERL-876

Fixed bug in seq_trace:set_token(label,Term) which could cause VM crash if Term was heap allocated (not an atom, small integer, local pid or port). Bug exists since OTP 21.0 when terms other than small integers were first allowed as labels.

Own Id: OTP-15849 Aux Id: ERL-700

Extra -mode flags given to erl are ignored with a warning.

Own Id: OTP-15852

Don't loop indefinitely when --enable-pgo is given to configure, but compiler does not support pgo.

Own Id: OTP-15853 Aux Id: PR-2254

Fix seq_trace:print/2 not to raise badarg exception if label is not a small integer. Bug exists since OTP 21.0.

Own Id: OTP-15859 Aux Id: ERL-700

Fixed hipe_flush_icache_range for non-Linux OS on ARM.

Own Id: OTP-15874 Aux Id: ERL-958, PR-2266

The fix in OTP-15871 was too conservative and disabled the offending load-time optimization in some cases where it was safe.

Own Id: OTP-15881

Upgraded the ERTS internal PCRE library from version 8.42 to version 8.43. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.

Own Id: OTP-15889

Fix race condition when closing a socket while using {active,N} on Windows.

Own Id: OTP-15901 Aux Id: ERL-960 PR-2272

Allow more than one -config command line option to erl on Windows to conform with other OS.

Own Id: OTP-15918 Aux Id: ERL-912

Fix so that ERL_FLAGS environment variable does not interfere with command line arguments. Before this fix you could write:

ERL_FLAGS="10" erl +S

and erlang would start as if +S had been given the argument 10.

Own Id: OTP-15931

The bug with ID ERL-717 has been fixed. The functions io:columns() and io:rows() only worked correctly inside interactive erlang shells before this fix. These functions returned {error,enotsup} before this fix even if stdout and stdin were connected to a terminal when they were invoked from an escript or a program started with e.g., erl -noshell.

Own Id: OTP-15959 Aux Id: ERL-717

Do not use named label in ethread.c inline assemble. This allows erts to be compiled using gcc 9.1.0 with LTO enabled.

Own Id: OTP-15971 Aux Id: PR-2333

erlang:fun_to_list/1 will now escape the module and function name when necessary.

Own Id: OTP-15975 Aux Id: ERL-1009

process_info(P,binary) would neglect to look through heap fragments, potentially missing a few binaries associated with the process.

Own Id: OTP-15978 Aux Id: ERIERL-366

HiPE is now automatically disabled on systems with non-glibc implementation (for instance musl). This is because musl does not provide the API's for guaranteeing that signals are delivered on the correct native stack.

Own Id: OTP-16037

Fixed bug triggered if a process is killed during call to persistent_term:put or persistent_term:erase.

Own Id: OTP-16041

Add units to all memory slogans in the crash dump documentation.

Own Id: OTP-16042

Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.

Own Id: OTP-16058 Aux Id: PR-2382

Fixed bug related to an exiting process sending EXIT and DOWN signals to remote linked/monitored processes. Bugs exists since OTP 22.0.

Own Id: OTP-16060

### Improvements and New Features

erlc can now automatically use a compile server to avoid starting an Erlang system for each file to be compiled in a multi-file project. See the documentation for how to enable it.

Own Id: OTP-15738 Aux Id: PR-2361

The possibility to send ancillary data, in particular the TOS field, has been added to gen_udp:send/4,5.

Own Id: OTP-15747 Aux Id: ERIERL-294

The net module has been split into 'net' (kernel) and prim_net (preloaded).

Own Id: OTP-15765

Socket counters now works as expected and can also be extracted with the (new) info function.

Own Id: OTP-15818

re:run() now avoids validating utf8 in the subject more than once in the same call. This validation could previously be performed multiple times when the global option was passed.

Own Id: OTP-15831 Aux Id: ERL-876

The un-documented function erlang:dist_get_stat/1 now returns the real value of what the distribution queue contains instead of a boolean.

Own Id: OTP-15905 Aux Id: PR-2270

ETS ordered_set tables with write_concurrency enabled has got a performance issue fixed. There were no limits for the values of internal statistics counters before this fix. This could result in that the data structure sometimes reacted slowly to a change in how many parallel processes were using it.

Own Id: OTP-15906

Optimize the reception of large distribution messages.

Own Id: OTP-15926 Aux Id: PR-2291

Binary matching and functions like split_binary/2 will now create heap binaries when the results are small enough, reducing the chances of small sub-binaries keeping large binaries alive.

Own Id: OTP-15977 Aux Id: ERIERL-366

Fixed rare emulator crash in instrument:allocations/0-1.

Own Id: OTP-15983

Ports could pass very small binaries as reference counted off heap binaries to processes. This could cause an unnecessary large memory usage and an unnecessary load on the binary allocator. Small binaries are now always passed as heap binaries to processes.

Own Id: OTP-16001 Aux Id: ERIERL-366

unicode:characters_to_binary() could return very small binaries as reference counted off heap binaries. This could cause an unnecessary large memory usage and an unnecessary load on the binary allocator. Small binaries are now always returned as heap binaries.

Own Id: OTP-16002 Aux Id: ERIERL-366

Improved erl_nif documentation regarding on_load and Erlang stub/fallback functions.

Own Id: OTP-16028 Aux Id: PR-2362

New feature ets:info(_, binary) to get information about all reference counted binaries kept by a table. This is the same kind of debug information that process_info(_, binary) returns for a process.

Own Id: OTP-16035 Aux Id: ERIERL-366

## Erts 10.4.4

### Fixed Bugs and Malfunctions

An invalid value test caused the socket:setopt(Socket, ip, add_membership, ip_mreq()) to fail with badarg. The same for drop_membership.

Own Id: OTP-15908 Aux Id: ERL-980

Fixed bug causing VM crash when doing textual dump of a process containing an unhandled monitor down signal. Textual process dumps can be done with erlang:system_info(procs), trace feature process_dump, Erlang shell break menu and a crashdump. Bug exist since OTP 21.0.

Own Id: OTP-15909 Aux Id: ERL-979

lists:subtract/2 would produce incorrect results for some inputs on 64-bit platforms.

Own Id: OTP-15938 Aux Id: ERL-986

Fixed a bug in the loader that was similar to OTP-15938, yielding incorrect code for some inputs on 64-bit platforms.

Own Id: OTP-15939

Fixed bug causing scheduler threads in rare cases to block spinnning indefinitely. Bug exists since OTP 21.0.

Own Id: OTP-15941 Aux Id: PR-2313

## Erts 10.4.3

### Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.

Own Id: OTP-15819 Aux Id: ERL-944

The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.

Own Id: OTP-15867 Aux Id: ERIERL-373

## Erts 10.4.2

### Fixed Bugs and Malfunctions

Fixed process_info(Pid,reductions) to not categorically increase reduction count of the measured process Pid. Repeated reduction measure of an idle process will most often (but not guaranteed) return the same value, like it behaved before OTP 21.3.8.

Own Id: OTP-15865 Aux Id: ERL-964

Fixed an incorrect load-time optimization that could cause a crash when extracting deeply nested tuple elements.

Own Id: OTP-15871 Aux Id: ERIERL-374

Fix bug causing VM crash when pressing P for "proc info" in Erlang shell break menu. Bug exists since OTP 22.0.

Own Id: OTP-15873 Aux Id: ERL-965

## Erts 10.4.1

### Fixed Bugs and Malfunctions

In nested use of try/catch, rethrowing an exception using erlang:raise/3 with a different class would not always be able to change the class of the exception.

Own Id: OTP-15834 Aux Id: ERIERL-367

## Erts 10.4

### Fixed Bugs and Malfunctions

Do not allocate new bitstring/binary when an empty binary is appended.

Own Id: OTP-15535 Aux Id: PR-2055

Document that process_info(_, current_function) can return {current_function, undefined} in case of execution of native code.

Own Id: OTP-15543 Aux Id: PR-2089

Fixed bug in ets:select, ets:match and friends which could cause the table to remain fixated (as if ets:safe_fixtable had been called) after the call returned. This could happen for protected tables if another concurrent running process transferred table ownership to the process during its ets:select/match call. Ownership can be transferred using either ets:give_away or the heir table option.

Own Id: OTP-15672

Fixed a Windows-specific bug in file:list_dir/1 that caused it to misbehave on network shares.

Own Id: OTP-15693

Fixed bug when calling enif_whereis_* from NIF resource destructor. Symptoms could be emulator crash or hanging scheduler threads.

Own Id: OTP-15694 Aux Id: ERL-863

Fixed a bug in the error case of apply/3, where the exception would erroneously have an empty argument list in some cases.

Own Id: OTP-15698

A bug has been fixed in the maps implementation that could cause a crash or memory usage to grow until the machine ran out of memory. This could happen when inserting a new key-value pair with a key K1 containing a binary B1 into a map M having a key K2 with a binary B2 if the following conditions were met:

B1 =/= B2 size(B1) >= 4294967296 size(B2) >= 4294967296 size(M) >= 32 (size(B1) rem 4294967296) == (size(B2) rem 4294967296) the first (size(B1) rem 4294967296) bytes are the same both in B1 and B2 substituting B1 in K1 with B2 would create a term with the same value as K2

The root cause of the problem is that the maps implementation only hashed the first (X rem 4294967296) bytes of binaries so that different binaries could get the same hash value independently of the hash seed.

Own Id: OTP-15707

term_to_binary() and distributed sends will now throw a system_limit exception instead of producing erroneous results when trying to encode a binary larger than 4 GB.

Own Id: OTP-15708

The vxworks configure has been updated to respect the environment CFLAGS.

Own Id: OTP-15773

Fix configure to not enable PGO (profile guided optimizations) when linking of the PGO binary fails. For instance this happens when there is no gcov lib installed.

Own Id: OTP-15788

Fix bug on OpenBSD where sockets using active, true or active, N could cause the system to live lock. The bug was introduced in erts-10.2 (OTP-21.2).

Own Id: OTP-15791

### Improvements and New Features

Add support for Erlang Distribution protocol to split the payload of large signals into several fragments. This allows other processes to communicate uninterrupted during the transmission of these signals.

Own Id: OTP-13397

A simple socket API is provided through the socket module. This is a low level API that does *not* replace gen_[tcp|udp|sctp]. It is intended to *eventually* replace the inet driver, but not the high level gen-modules (gen_tcp, gen_udp and gen_sctp). It also provides a basic API that facilitates the implementation of other protocols, that is TCP, UDP and SCTP.

Known issues are; No support for the Windows OS (currently).

Own Id: OTP-14831

Added NIF functions enif_set_pid_undefined, enif_is_pid_undefined and enif_compare_pids.

Own Id: OTP-15011 Aux Id: PR-2147

Underutilized memory segments (carriers) can now move between all allocator instances, rather than just between instances of the same type, which greatly reduces memory usage in some scenarios.

Own Id: OTP-15063

The emulator will now mark free blocks in pooled carriers with madvise(2) + MADV_FREE (or similar), letting the OS reclaim the associated physical memory if necessary.

Own Id: OTP-15075

New ERL_NIF_SELECT_CANCEL feature added to enif_select in order to cancel (or "deselect") a read or write event on a previously selected file descriptor.

Own Id: OTP-15095

ETS option write_concurrency now also affects and improves the scalability of ordered_set tables. The implementation is based on a data structure called contention adapting search tree, where the lock granularity adapts to the actual amount of concurrency exploited by the applications in runtime.

Own Id: OTP-15128

Build configuration of the crypto application has been moved from the erts application into the crypto application.

Own Id: OTP-15129

Anonymous functions that don't capture environment are now created at load-time instead of in run-time.

Own Id: OTP-15195 Aux Id: PR-1812

Optimize updates of maps with identical keys and values. E.g. in the example below the original Map will be reused as the return of the update.

1> Map = #{ a => b }. #{ a => b } 2> Map#{ a := b }.

Own Id: OTP-15211 Aux Id: PR-1889

Optimize binary:match/2 and binary:matches/2 to use memchr internally.

Own Id: OTP-15238 Aux Id: PR-1803

The runtime system used to terminate when a message larger than 2 Gb was passed over the distribution. The send operation will now instead throw a system_limit exception.

Own Id: OTP-15261

Change the first module called by erts to be named erl_init instead of otp_ring0. systools in sasl have been updated to reflect this change.

Own Id: OTP-15336 Aux Id: PR-1825

Minor adjustments made to build system for parallel configure.

Own Id: OTP-15340 Aux Id: OTP-14625

Two new NIF interface functions enif_select_read and enif_select_write. They are similar to existing enif_select but allow a custom event message as an argument.

Own Id: OTP-15349 Aux Id: PR-2084

The embedded copy of zlib has been updated from 1.2.8 to 1.2.11.

Note that this copy is only used as a fallback when the target platform doesn't provide any zlib development libraries. If your system provides zlib then it will be used even if it is older than 1.2.11.

Own Id: OTP-15351 Aux Id: ERL-749

New NIF function enif_make_monitor_term.

Own Id: OTP-15362 Aux Id: PR-2127

Appending lists (The ++ operator) will now yield properly on large inputs.

Own Id: OTP-15427

The length/1 BIF used to calculate the length of the list in one go without yielding, even if the list was very long. In OTP 22, length/1 will yield when called with long lists.

Own Id: OTP-15439

Processes sending messages are now punished with a reduction cost based on message size. That is, a process sending a large message will yield earlier than before.

Own Id: OTP-15513 Aux Id: ERL-773

The transitory emulator option +ztma true (introduced in OTP 21.3) has been removed.

Own Id: OTP-15581 Aux Id: OTP-15580

In OTP 22, HiPE (the native code compiler) is not fully functional. The reasons for this are:

There are new BEAM instructions for binary matching that the HiPE native code compiler does not support.

The new optimizations in the Erlang compiler create new combination of instructions that HiPE currently does not handle correctly.

If erlc is invoked with the +native option, and if any of the new binary matching instructions are used, the compiler will issue a warning and produce a BEAM file without native code.

Own Id: OTP-15596

The termination behaviour of processes has changed to allow processes to yield while sending link exit/monitor down signals.

The erl crash dump has been expanded to now also include processes that are termeinating but have not yet terminated.

Own Id: OTP-15610

The dist messages EXIT, EXIT2 and MONITOR_DOWN have been updated with new versions that send the reason term as part of the payload of the message instead of as part of the control message.

The old versions are still present and can be used when communicating with nodes that don't support the new versions.

Own Id: OTP-15611

When sending messages, exit, exit2 and monitor down distributed signals, the process sending will now yield appropriately.

This means that a terminating process will yield and possibly be suspended on busy distribution entries while they are terminating. This means that any memory held by such processes will not be released until after all exit/monitor down signals have been sent.

Own Id: OTP-15612

All external pids/ports/refs created by erlang:list_to_pid/port/ref debug functions now compare equal to any other pid/port/ref with the same number from that node.

Before this change they compared differently because the node creation of the pid/port/ref did not compare equal to any real pid/port/ref creation.

This will mostly effect pids/ports/refs typed in the shell.

Own Id: OTP-15613

The persistent_term functions put/2 and erase/1 are now yielding.

Own Id: OTP-15615

A new erlang:dist_ctrl_set_opt(DHandle, get_size, Value) option has been added. This option makes it possible to configure the distribution channel identified by DHandle so that erlang:dist_ctrl_get_data(DHandle) also returns the size of the data to pass over the channel.

Own Id: OTP-15617

Previously, all ETS tables used centralized counter variables to keep track of the number of items stored and the amount of memory consumed. These counters can cause scalability problems (especially on big NUMA systems). This change adds an implementation of a decentralized counter and modifies the implementation of ETS so that ETS tables of type ordered_set with write_concurrency enabled use the decentralized counter. Experiments indicate that this change substantially improves the scalability of ETS ordered_set tables with write_concurrency enabled in scenarios with frequent ets:insert/2 and ets:delete/2 calls.

Own Id: OTP-15623 Aux Id: PR-2190

The iolist_size/1 function is now yielding which means that an Erlang/OTP system will be responsive even if the applications running on the system frequently call iolist_size/1 with large iolists.

Own Id: OTP-15631

A simple test suite for the net module has been added.

Own Id: OTP-15635

Added the NIF function enif_term_type, which helps avoid long sequences of enif_is_xyz by returning the type of the given term. This is especially helpful for NIFs that serialize terms, such as JSON encoders, where it can improve both performance and readability.

Own Id: OTP-15640

The last call optimization is now applied to BIFs. When calling a BIF in the tail position of a function, the return address and stack frame will now be discarded before calling the BIF. As a consequence of this change, the immediate caller of a tail-called BIF will no longer be available in stack backtraces.

Own Id: OTP-15674 Aux Id: PR-2177

Fix GC bug where distributed messages in a processes mailbox would cause extra GCs. This can be very expensive if there many messages in the mailbox.

Own Id: OTP-15703

Internal documentation has now been added to the Erts and Compiler applications.

The internal documents for Erts describe miscellaneous interesting implementation details. Those details can change at any time.

The internal documentation for Compiler documents the API for the Core Erlang modules. While we will not change those APIs without good reason, we don't give the same guarantees about backward compatibility as for the rest of the APIs in OTP.

Own Id: OTP-15715

The performance of non-bignum integer arithmetic has been improved.

Own Id: OTP-15740

The -remsh option to erl now automatically adds the local systems hostname to the target node if no nodename is given. e.g.

erl -name foo -remsh bar
erl -sname foo -remsh bar

Own Id: OTP-15794 Aux Id: PR-2219

## Erts 10.3.5.19

### Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.

Own Id: OTP-17379 Aux Id: PR-4804

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).

Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

## Erts 10.3.5.18

### Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.

garbage-collect request. Sent from one process to another using one of the garbage_collect() BIFs. check-process-code request. Sent from one process to another using one of the check_process_code() BIFs. is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF. process-info reply. Sent as a response to a process calling one of the process_info() BIFs. port-command reply. Sent as a response to a process calling one of the port_command() BIFs. port-connect reply. Sent as a response to a process calling the port_connect() BIF. port-close reply. Sent as a response to a process calling the port_close() BIF. port-control reply. Sent as a response to a process calling the port_control() BIF. port-call reply. Sent as a response to a process calling the port_call() BIF. port-info reply. Sent as a response to a process calling one of the port_info() BIFs.

Own Id: OTP-17291

A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.

Own Id: OTP-17307

A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.

Own Id: OTP-17349

## Erts 10.3.5.17

### Fixed Bugs and Malfunctions

Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.

Own Id: OTP-17253

### Improvements and New Features

Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.

Own Id: OTP-17244

## Erts 10.3.5.16

### Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:

Termination of a distribution controller process Disabling of the distribution on a node Gathering of memory allocator information using the instrument module Enabling, disabling, and gathering of msacc information Delivery of 'CHANGE' messages when time offset is monitored A call to erlang:cancel_timer() A call to erlang:read_timer() A call to erlang:statistics(io | garbage_collection | scheduler_wall_time) A call to ets:all() A call to erlang:memory() A call to erlang:system_info({allocator | allocator_sizes, _}) A call to erlang:trace_delivered()

The bug existed on runtime systems running on all types of hardware except for x86/x86_64.

Own Id: OTP-17185

## Erts 10.3.5.15

### Fixed Bugs and Malfunctions

Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.

Own Id: OTP-16869 Aux Id: ERL-1337

The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.

Own Id: OTP-17080

The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.

Own Id: OTP-17088 Aux Id: ERIERL-580

## Erts 10.3.5.14

### Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.

Own Id: OTP-16780 Aux Id: PR-2701

The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.

Own Id: OTP-16866 Aux Id: ERL-1355

Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.

Own Id: OTP-16870

Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.

Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763

## Erts 10.3.5.13

### Fixed Bugs and Malfunctions

An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.

Own Id: OTP-16766 Aux Id: ERL-1304

NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.

Own Id: OTP-16772 Aux Id: ERL-1304

## Erts 10.3.5.12

### Fixed Bugs and Malfunctions

The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.

The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.

Own Id: OTP-16639 Aux Id: ERL-1236

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.

Own Id: OTP-16640 Aux Id: OTP-16193

The VM could potentially crash when checking process code of a process that terminated while executing a dirty NIF. The checking of process code is part of a code purge operation.

Own Id: OTP-16641

System tasks of low priority were not interleaved with normal priority system tasks as they should. This could potentially delay garbage collection of another process longer than intended if the garbage collection was requested from a low priority process.

Own Id: OTP-16642

## Erts 10.3.5.11

### Fixed Bugs and Malfunctions

re:run(Subject, RE, [unicode]) returned nomatch instead of failing with a badarg error exception when Subject contained illegal utf8 and RE was passed as a binary. This has been corrected along with corrections of reduction counting in re:run() error cases.

Own Id: OTP-16553

Fixed a bug that could cause the emulator to crash when purging modules or persistent terms.

Own Id: OTP-16555 Aux Id: ERL-1188

## Erts 10.3.5.10

### Fixed Bugs and Malfunctions

Fixed bug in ets:update_counter/4, when called with an invalid UpdateOp and a Key that does not exist, causing ets:info(T,size) to return incorrect values. Bug exists since OTP-19.0.2.

Own Id: OTP-16404 Aux Id: ERL-1127

A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.

Own Id: OTP-16446 Aux Id: ERL-1157

Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.

Own Id: OTP-16481

## Erts 10.3.5.9

### Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.

Own Id: OTP-16436 Aux Id: ERL-1152

Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.

Own Id: OTP-16438

## Erts 10.3.5.8

### Fixed Bugs and Malfunctions

Taking a scheduler offline could cause timers set while executing on that scheduler to be delayed until the scheduler was put online again. This bug was introduced in ERTS version 10.0 (OTP 21.0).

Own Id: OTP-16371

A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.

Own Id: OTP-16379

## Erts 10.3.5.7

### Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.

Own Id: OTP-16193

Fix bug causing VM crash due to memory corruption of distribution entry. Probability of crash increases if Erlang distribution is frequently disconnected and reestablished towards same node names. Bug exists since OTP-21.0.

Own Id: OTP-16224 Aux Id: ERL-1044

Fix bug where the receive marker used by the runtime to do the receive queue optimization could be incorrectly set. The symptom of this would be that a message that should match in a receive never matches.

The bug requires the OTP-22 compiler and multiple selective receives to trigger. See OTP-16219 for details about the bug fix in the compiler.

Own Id: OTP-16241 Aux Id: ERL-1076 OTP-16219

Fixed bug causing crash of VM built with configuration --enable--sharing-preserving. Provoked when a sent message contains both a bit string and the heap binary (< 65 bytes) which the bit string was matched from. Bug exists since OTP-19.0 but has seen to be easier to provoke since OTP-22.1.

Own Id: OTP-16265 Aux Id: ERL-1064

## Erts 10.3.5.6

### Fixed Bugs and Malfunctions

Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.

Own Id: OTP-16058 Aux Id: PR-2382

When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.

Own Id: OTP-16107 Aux Id: ERL-1049

## Erts 10.3.5.5

### Fixed Bugs and Malfunctions

process_info(P,binary) would neglect to look through heap fragments, potentially missing a few binaries associated with the process.

Own Id: OTP-15978 Aux Id: ERIERL-366

Fixed bug triggered if a process is killed during call to persistent_term:put or persistent_term:erase.

Own Id: OTP-16041

### Improvements and New Features

Fixed rare emulator crash in instrument:allocations/0-1.

Own Id: OTP-15983

## Erts 10.3.5.4

### Fixed Bugs and Malfunctions

Fixed bug causing VM crash when doing textual dump of a process containing an unhandled monitor down signal. Textual process dumps can be done with erlang:system_info(procs), trace feature process_dump, Erlang shell break menu and a crashdump. Bug exist since OTP 21.0.

Own Id: OTP-15909 Aux Id: ERL-979

lists:subtract/2 would produce incorrect results for some inputs on 64-bit platforms.

Own Id: OTP-15938 Aux Id: ERL-986

Fixed a bug in the loader that was similar to OTP-15938, yielding incorrect code for some inputs on 64-bit platforms.

Own Id: OTP-15939

Fixed bug causing scheduler threads in rare cases to block spinnning indefinitely. Bug exists since OTP 21.0.

Own Id: OTP-15941 Aux Id: PR-2313

## Erts 10.3.5.3

### Fixed Bugs and Malfunctions

If you set {linger,{true,0}} on a gen_tcp listen socket, accept a connection on that socket, and then close the accepted socket, now the linger zero setting is transferred to the accepted socket. Before this correction that information was lost and the close behaviour on the accepted socket incorrect.

Own Id: OTP-15370 Aux Id: ERIERL-353

Fixed process_info(Pid,reductions) to not categorically increase reduction count of the measured process Pid. Repeated reduction measure of an idle process will most often (but not guaranteed) return the same value, like it behaved before OTP 21.3.8.

Own Id: OTP-15865 Aux Id: ERL-964

The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.

Own Id: OTP-15867 Aux Id: ERIERL-373

### Improvements and New Features

The possibility to send ancillary data, in particular the TOS field, has been added to gen_udp:send/4,5.

Own Id: OTP-15747 Aux Id: ERIERL-294

## Erts 10.3.5.2

### Fixed Bugs and Malfunctions

In nested use of try/catch, rethrowing an exception using erlang:raise/3 with a different class would not always be able to change the class of the exception.

Own Id: OTP-15834 Aux Id: ERIERL-367

Fixed bug in seq_trace:set_token(label,Term) which could cause VM crash if Term was heap allocated (not an atom, small integer, local pid or port). Bug exists since OTP 21.0 when terms other than small integers were first allowed as labels.

Own Id: OTP-15849 Aux Id: ERL-700

Fix seq_trace:print/2 not to raise badarg exception if label is not a small integer. Bug exists since OTP 21.0.

Own Id: OTP-15859 Aux Id: ERL-700

## Erts 10.3.5.1

### Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.

Own Id: OTP-15819 Aux Id: ERL-944

## Erts 10.3.5

### Fixed Bugs and Malfunctions

Fixed more bugs in process_info(reductions) causing it to sometimes behave non-monotonic. That is, a subsequent call toward the same process could return a lower reduction value.

Own Id: OTP-15793 Aux Id: ERIERL-337, OTP-15709

## Erts 10.3.4

### Fixed Bugs and Malfunctions

Add missing documentation of new external tags NEW_PID, NEW_PORT and NEWER_REFERENCE introduced in OTP 19.

These new tags are planned to be "activated" in OTP 23 when distribution capability flag DFLAG_BIG_CREATION becomes mandatory. Older nodes (>= 19) are able to decode these new tags and send them back to the new node. Nodes older than OTP 23 will however never encode their own local pids, ports and references using the new tags.

Own Id: OTP-15766

## Erts 10.3.3

### Fixed Bugs and Malfunctions

Fix erlang:open_port/2 with the fd option to correctly cleanup the pollset when the port is closed. Before this fix there would be error printouts sent to logger when the same fd was reused in a new port.

Own Id: OTP-15753 Aux Id: ERL-900

## Erts 10.3.2

### Fixed Bugs and Malfunctions

Fixed a bug in seq_trace:reset_trace/0 that could crash the emulator.

Own Id: OTP-15704

Fixed bug in process_info(reductions) causing it to sometimes return invalid results.

Own Id: OTP-15709 Aux Id: ERIERL-337

## Erts 10.3.1

### Fixed Bugs and Malfunctions

If a suspend/resume signal pair was sent to a process while it was executing dirty, the receiving process could later end up in a suspended state indefinitely. This bug was introduced in ERTS version 10.0 (OTP 21.0).

Suspend/resume signals are sent from erlang:suspend_process()/erlang:resume_process(). The dbg trace tool utilize this functionality and could thus trigger this bug.

Own Id: OTP-15688

Fix a possible deadlock when terminating the ERTS caused by a dirty scheduler not releasing it's run-queue lock when terminating.

Own Id: OTP-15690 Aux Id: PR-2172

## Erts 10.3

### Fixed Bugs and Malfunctions

When multiplying a number by itself, a word beyond the number on the heap could be read (and ignored). This bug was extremely unlikely to actually cause a real problem.

Own Id: OTP-15484

Fix bug where doing seq_trace:reset_trace() while another process was doing a garbage collection could cause the run-time system to segfault.

Own Id: OTP-15490

Fix reading of ancillary data from packet oriented sockets on old Linux kernel versions. Without this fix, getting the data would cause the port to enter an infinite loop.

Own Id: OTP-15494

Fix bug where crash dumping or doing erlang:system_info(procs) while another process was doing a garbage collection could cause the run-time system to segfault.

Own Id: OTP-15527

Fix erlang:system_info(kernel_poll) to return correct value. Before this fix, the call always returned false.

Own Id: OTP-15556

Fix bug in enif_make_map_from_arrays that would produce broken maps when number of keys were 32. Bug exists since OTP 21.0.

Own Id: OTP-15567

Fix a bug in binary:encode_unsigned that may cause a read of uninitialized memory.

The bug existed since the function was added (OTP R16B02).

Own Id: OTP-15583 Aux Id: PR-2118

Fixed a bug that could cause heart to kill an exiting node before it had time to flush all buffered writes. If environment variable HEART_KILL_SIGNAL=SIGABRT was set a superfluous core dump could also be generated.

Own Id: OTP-15599 Aux Id: ERIERL-298

Fix enif_consume_timeslice to be a no-op on dirty scheduler and not crash debug compiled emulator.

Own Id: OTP-15604

Fixed macro redefinition warnings.

Own Id: OTP-15629

to_erl fixed to not garble terminal input beyond 7-bit ASCII.

Own Id: OTP-15650 Aux Id: ERL-854, PR-2161

Minor fixes for make clean.

Own Id: OTP-15657

Fixed a bug in all ets:select* and ets:match* functions that could in some rare cases lead to very poor performance.

Own Id: OTP-15660 Aux Id: ERL-869

### Improvements and New Features

Add erlang:system_flag(system_logger, Pid) and erlang:system_info(system_logger). This system_flag can be used to set the process that will receive the logging messages generated by ERTS.

Own Id: OTP-15375

integer_to_list/2 and integer_to_binary/2 are now implemented in C, improving their performance.

Own Id: OTP-15503 Aux Id: PR-2052

Improved term_to_binary to do more fair reduction count and yielding when encoding large byte lists (strings).

Own Id: OTP-15514 Aux Id: ERL-774

Made internal port drivers more robust against erlang:port_control with invalid arguments and added documentation warnings about such abuse.

Own Id: OTP-15555 Aux Id: ERIERL-231

Fix bug on NetBSD where the exit_status from a port program would never be sent.

Own Id: OTP-15558 Aux Id: ERL-725

There is a new function persistent:term(Key, Default) to allow specifying a default when looking up a persistent term.

Own Id: OTP-15576 Aux Id: ERL-843

A transitory emulator option '+ztma true' has been added to allow running existing BEAM code that relies on "tuple calls" (dispatch on parameterized modules) which has been compiled under OTP 20 or earlier. This option will be removed in OTP 22, so such modules should eventually be recompiled with the +tuple_calls option.

Own Id: OTP-15580 Aux Id: PR-2113

## Erts 10.2.5

### Fixed Bugs and Malfunctions

Fixes of install/release phase in build system.

The source tree was modified when installing/releasing and/or applying a patch. Some files were installed with wrong access rights. If applying a patch (using otp_patch_apply) as another user (except root) than the user that built the source, the documentation was not properly updated.

Own Id: OTP-15551

Setting the recbuf size of an inet socket the buffer is also automatically increased. Fix a bug where the auto adjustment of inet buffer size would be triggered even if an explicit inet buffer size had already been set.

Own Id: OTP-15651 Aux Id: ERIERL-304

Reading from UDP using active true or active N mode has been optimized when more packets than specified by read_packets are available on the socket.

Own Id: OTP-15652 Aux Id: ERIERL-304

## Erts 10.2.4

### Fixed Bugs and Malfunctions

When using the {linger,{true,T}} option; gen_tcp:listen/2 used the full linger time before returning for example eaddrinuse. This bug has now been corrected.

Own Id: OTP-14728 Aux Id: ERIERL-303

## Erts 10.2.3

### Fixed Bugs and Malfunctions

Fix bug where doing a gen_tcp:send on a socket with delay_send set to true could cause a segfault if the other side closes the connection.

Bug was introduced in erts-10.2 (OTP-21.2).

Own Id: OTP-15536 Aux Id: ERL-827

Fix a race condition when a port program closes that could result in the next started port to hang during startup.

When this fault happens the following error is normally (but not always) logged:

=ERROR REPORT==== 14-Jan-2019::10:45:52.868246 ===
Bad input fd in erts_poll()! fd=11, port=#Port<0.505>, driver=spawn, name=/bin/sh -s unix:cmd

Bug was introduced in erts-10.0 (OTP-21.0).

Own Id: OTP-15537

Fix a bug where polling for external events could be delayed for a very long time if all active schedulers were 100% loaded.

Bug was introduced in erts-10.2 (OTP-21.2).

Own Id: OTP-15538 Aux Id: ERIERL-229

## Erts 10.2.2

### Fixed Bugs and Malfunctions

Fixed a crash when dangling files were closed after init:restart/0.

Own Id: OTP-15495 Aux Id: ERL-821

A bug that could cause dirty schedulers to become unresponsive has been fixed.

Own Id: OTP-15509 Aux Id: PR-2027, PR-2093

## Erts 10.2.1

### Fixed Bugs and Malfunctions

Fixed bug on big endian architectures when changing file permissions or ownership with file:change_mode, change_owner, change_group or write_file_info. Bug exists since OTP-21.0.

Own Id: OTP-15485

Fixed bug in atomics with option {signed,false} when returned values are (1 bsl 63) or larger. Could cause heap corruption leading to VM crash or other unpleasant symptoms. Bug exists since OTP-21.2 when module atomics was introduced.

Own Id: OTP-15486 Aux Id: PR-2061

Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-15487 Aux Id: ERL-804

## Erts 10.2

### Fixed Bugs and Malfunctions

When a process was waiting for a TCP socket send operation to complete, and another process closed the socket during that send, the sending process could hang. This bug has now been corrected.

Own Id: OTP-12242 Aux Id: ERL-561

Document bit_size in match specifications and allow it in ets:fun2ms.

Own Id: OTP-15343 Aux Id: PR-1962

Fixed bug in ets:select_replace when called with a fully bound key could cause a following call to ets:next or ets:prev to crash the emulator or return invalid result.

Own Id: OTP-15346

When a module has been purged from memory, any literals belonging to that module will be copied to all processes that hold references to them. The max heap size limit would be ignored in the garbage collection initiated when copying literals to a process. If the max heap size was exceeded, the process would typically be terminated in the following garbage collection. Corrected to terminate the process directly if copying a literal would exceed the max heap size.

Own Id: OTP-15360

Fix compilation of run_erl on Solaris 11.4 and later.

Own Id: OTP-15389

Fixed a bug where lists:reverse/1-2 could use far too many reductions. This bug was introduced in OTP 21.1.

Own Id: OTP-15436

Fixed a bug where a dirty scheduler could stay awake forever if a distribution entry was removed as part of a dirty GC.

Own Id: OTP-15446 Aux Id: PR-2024

Fix microstate accounting handing in various places. Most importantly the GC states when the GC is run on a dirty scheduler are now managed correctly.

Own Id: OTP-15450 Aux Id: ERIERL-229

Fixed bug in file:sendfile when the send operation failed. For sockets in active modes it could cause emulator crash or a hanging call. For sockets with {active,false} an unexpected {inet_reply, _, _} message could be sent to the calling process. The bug exists since OTP-21.0.

Own Id: OTP-15461 Aux Id: ERL-784

The erts configure script has been updated to reject any CFLAGS that does not have -O. This in order to prevent the common mistake of forgetting to add -O2 to custom CFLAGS.

Own Id: OTP-15465

Fix reduction count in lists:member/2

Own Id: OTP-15474 Aux Id: ERIERL-229

### Improvements and New Features

New counters and atomics modules supplies access to highly efficient operations on mutable fixed word sized variables.

Own Id: OTP-13468

There is a new module persistent_term that implements a term storage suitable for terms that are frequently used but never or infrequently updated. Lookups are done in constant time without copying the terms.

Own Id: OTP-14669 Aux Id: PR-1989

A function inet:getifaddrs/1 that takes a list with a namespace option has been added, for platforms that support that feature, for example Linux (only?).

Own Id: OTP-15121 Aux Id: ERIERL-189, PR-1974

Added the nopush option for TCP sockets, which corresponds to TCP_NOPUSH on *BSD and TCP_CORK on Linux.

This is also used internally in file:sendfile to reduce latency on subsequent send operations.

Own Id: OTP-15357 Aux Id: ERL-698

List subtraction (The -- operator) will now yield properly on large inputs.

Own Id: OTP-15371

Optimize handling of send_delay for tcp sockes to better work with the new pollthread implementation introduced in OTP-21.

Own Id: OTP-15471 Aux Id: ERIERL-229

Optimize driver_set_timer with a zero timeout to short-circuit and not create any timer structure, but instead schedule the timer immediately.

Own Id: OTP-15472 Aux Id: ERIERL-229

Add erl_xcomp_code_model_small as a cross configure variable in order to let the emulator be build with the assumption that a small code model will be used on the target machine.

Own Id: OTP-15473 Aux Id: ERIERL-229

Add a new pollset that is made to handle sockets that use {active, true} or {active, N}. The new pollset will not be polled by a pollthread, but instead polled by a normal scheduler.

This change was made because of the overhead associated with constantly having to re-apply the ONESHOT mechanism on fds that all input events were interesting.

The new pollset is only active on platforms that support concurrent kernel poll updates, i.e. Linux and BSD.

Own Id: OTP-15475 Aux Id: ERIERL-229

Fix bug where emulator would segfault if a literal message was sent when sequence tracing was enabled.

Own Id: OTP-15478 Aux Id: ERL-741

## Erts 10.1.3

### Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation

Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.

Own Id: OTP-15430 Aux Id: ERIERL-237

## Erts 10.1.2

### Fixed Bugs and Malfunctions

Fixed a rare bug where files could be closed on a normal instead of an IO scheduler, resulting in system instability if the operation blocked.

Own Id: OTP-15421

## Erts 10.1.1

### Fixed Bugs and Malfunctions

A bug where the socket option 'pktoptions' caused a read of uninitialized memory has been fixed. Would cause malfunction on FreeBSD.

Own Id: OTP-14297 Aux Id: OTP-15141

Fixed a memory leak on errors when reading files.

Own Id: OTP-15318

File access through UNC paths works again on Windows. This regression was introduced in OTP 21.

Own Id: OTP-15333 Aux Id: ERL-737

## Erts 10.1

### Fixed Bugs and Malfunctions

Fix the seq_trace token to not be cleared when a process receives messages sent by erts. Some examples of when this could happen is all port BIFs, i.e. open_port, port_command etc etc.

Fix so that messages sent by nifs can be traced using normal and seq_trace tracing.

Own Id: OTP-15038 Aux Id: ERL-602

Fixed specs and documentation for process_info item monitored_by to include port identifiers and nif resources as possible types.

Own Id: OTP-15180 Aux Id: ERL-648

Fix bug in generation of erl_crash.dump, which could cause VM to crash.

Bug exist since erts-9.2 (OTP-20.2).

Own Id: OTP-15181

Fix bug where ctrl-break or ctrl-c would not trigger the break mode properly on Windows. This bug was introduced in erts-10.0 (OTP-21).

Own Id: OTP-15205

Fix a performance bug for reception of UDP packages, where a memory buffer would be reallocated when it should not have been.

Introduce a limit on the maximum automatic increase of the UDP user-space buffer to the theoretical max of the network PATH, i.e. 65535.

Own Id: OTP-15206

Fix alignment of erts allocator state internally in erts. With the improper alignment the emulator would refuse to start when compiled with clang on 32-bit systems.

Own Id: OTP-15208 Aux Id: PR-1897 ERL-677

Fix bug where too many concurrent calls to erlang:open_port({spawn,"cmd"},...) would result in the emulator terminating with the reason "Failed to write to erl_child_setup: ". After this fix the open_port call will throw an emfile exception instead.

Own Id: OTP-15210

Upgraded the ERTS internal PCRE library from version 8.41 to version 8.42. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.

Own Id: OTP-15217

Fix open_port({fd,X,Y}, ...) to release the file descriptors from the pollset when closing the port. Without this fix the same file descriptor number could not be reused when doing multiple open_port and port_close sequences.

Own Id: OTP-15236 Aux Id: ERL-692

Fixed bug in float_to_list/2 and float_to_binary/2 with options [{decimals,0},compact] causing totally wrong results. Bug exists since OTP-21.0.

Own Id: OTP-15276 Aux Id: PR-1920

Fixed bug in erlang:memory causing ets to report too much. This small false memory leak (16 bytes each time) can only happen when a specific race condition occurs between scheduler threads on a table with option write_concurrency.

Own Id: OTP-15278

Minor configure test fixes

Own Id: OTP-15282

Improved robustness of distribution connection setup. In OTP-21.0 a truly asynchronous connection setup was introduced. This is further improvement on that work to make the emulator more robust and also be able to recover in cases when involved Erlang processes misbehave.

Own Id: OTP-15297 Aux Id: OTP-15279, OTP-15280

### Improvements and New Features

The socket options recvtos, recvttl, recvtclass and pktoptions have been implemented in the socket modules. See the documentation for the gen_tcp, gen_udp and inet modules. Note that support for these in the runtime system is platform dependent. Especially for pktoptions which is very Linux specific and obsoleted by the RFCs that defined it.

Own Id: OTP-15145 Aux Id: ERIERL-187

## Erts 10.0.8

### Fixed Bugs and Malfunctions

As of ERTS version 10.0 (OTP 21.0) the erl_child_setup program, which creates port programs, ignores TERM signals. This setting was unintentionally inherited by port programs. Handling of TERM signals in port programs has now been restored to the default behavior. That is, terminate the process.

Own Id: OTP-15289 Aux Id: ERIERL-235, OTP-14943, ERL-576

The fix made for OTP-15279 in erts-10.07 (OTP-21.0.8) was not complete. It could cause a new connection attempt to be incorrectly aborted in certain cases. This fix will amend that flaw.

Own Id: OTP-15296 Aux Id: OTP-15279, ERIERL-226

## Erts 10.0.7

### Fixed Bugs and Malfunctions

A process could get stuck in an infinite rescheduling loop between normal and dirty schedulers. This bug was introduced in ERTS version 10.0.

Thanks to Maxim Fedorov for finding and fixing this issue.

Own Id: OTP-15275 Aux Id: PR-1943

Garbage collection of a distribution entry could cause an emulator crash if net_kernel had not brought previous connection attempts on it down properly.

Own Id: OTP-15279 Aux Id: ERIERL-226

## Erts 10.0.6

### Fixed Bugs and Malfunctions

A race between termination of a process and resume of the same process via erlang:resume_process/1 could cause the VM to crash. This bug was introduced in erts version 10.0 (OTP 21.0).

Own Id: OTP-15237

When tracing on running, in trace events could be lost when a process was rescheduled between a dirty and a normal scheduler.

Own Id: OTP-15269 Aux Id: ERL-713

## Erts 10.0.5

### Fixed Bugs and Malfunctions

Fixed a bug which caused an emulator crash when enif_send() was called by a NIF that executed on a dirty scheduler. The bug was either triggered when the NIF called enif_send() without a message environment, or when the process executing the NIF was send traced.

Own Id: OTP-15223

Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.

Thanks to Simon Cornish for finding the bug and supplying a fix.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-15225

## Erts 10.0.4

### Fixed Bugs and Malfunctions

Fixed a bug that prevented the noshell option from working correctly on Mac OS X and BSD.

Own Id: OTP-15169

Fixed a crash when matching directly against a literal map using a single key that had been saved on the stack.

Own Id: OTP-15184

Fix node crash when passing a bad time option to file:read_file_info/2.

Own Id: OTP-15196

## Erts 10.0.3

### Fixed Bugs and Malfunctions

Fixed a scheduler bug that caused normal schedulers to run dirty code.

Own Id: OTP-15154

Fixed a bug in erlang:trace_info/2 which caused the emulator to crash when a bad argument was passed. The bug was introduced in ERTS version 10.0.

Own Id: OTP-15183 Aux Id: ERL-670

## Erts 10.0.2

### Fixed Bugs and Malfunctions

Fixed a rare bug that could cause processes to be scheduled after they had been freed.

Own Id: OTP-15067 Aux Id: ERL-573

Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.

Own Id: OTP-15158 Aux Id: ERL-654

## Erts 10.0.1

### Fixed Bugs and Malfunctions

The keys used in os:getenv and os:putenv are case-insensitive again on Windows.

Own Id: OTP-15147 Aux Id: ERL-644

## Erts 10.0

### Fixed Bugs and Malfunctions

The type specifications for file:posix/0 and inet:posix/0 have been updated according to which errors file and socket operations should be able to return.

Own Id: OTP-14019 Aux Id: ERL-550

Fix error printout from run_erl and a bug that could cause unintended fds to be leaked into the started program.

Own Id: OTP-14537 Aux Id: PR1529

File operations used to accept filenames containing null characters (integer value zero). This caused the name to be truncated and in some cases arguments to primitive operations to be mixed up. Filenames containing null characters inside the filename are now rejected and will cause primitive file operations to fail.

Also environment variable operations used to accept names and values of environment variables containing null characters (integer value zero). This caused operations to silently produce erroneous results. Environment variable names and values containing null characters inside the name or value are now rejected and will cause environment variable operations to fail.

Primitive environment variable operations also used to accept the $= character in environment variable names causing various problems. $= characters in environment variable names are now also rejected.

Also os:cmd/1 now reject null characters inside its command.

erlang:open_port/2 will also reject null characters inside the port name from now on.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14543 Aux Id: ERL-370

Fix bugs related to the bookkeeping of microstate accounting states.

Own Id: OTP-14652

os:putenv and os:getenv no longer access the process environment directly and instead work on a thread-safe emulation. The only observable difference is that it's not kept in sync with libc getenv(3) / putenv(3), so those who relied on that behavior in drivers or NIFs will need to add manual synchronization.

On Windows this means that you can no longer resolve DLL dependencies by modifying the PATH just before loading the driver/NIF. To make this less of a problem, the emulator now adds the target DLL's folder to the DLL search path.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14666

Corrected erlang:is_builtin(erlang, M, F) to return true for apply/2 and yield/0.

Own Id: OTP-14713 Aux Id: ERL-500

Fixed a bug where the PATH environment variable wasn't updated correctly on a release downgrade, effectively keeping the PATH of the new release.

Own Id: OTP-14719

A receive optimization that avoids scanning the entire message queue when receiving a message containing a freshly created reference could in rare circumstances (involving recursive calls to the functions that does the receive) cause the receive to hang. This has been corrected.

Own Id: OTP-14782 Aux Id: ERL-511

Fix building of Erlang/OTP on platforms which have small data area with short addressing. For example the PowerPC/RTEMS platform.

Own Id: OTP-14909 Aux Id: PR-1692

Fixed a crash when enif_make_binary is called with a binary produced by enif_inspect_binary in a different environment.

Own Id: OTP-14931

Fixed a crash when enif_make_binary is called more than once with a binary that had previously been added to an enif_ioq.

Own Id: OTP-14932

The erl_child_setup program now ignores SIGTERM signals.

Own Id: OTP-14943 Aux Id: ERL-576

Force 64-bit alignment on pre-allocators on architectures which needs it.

Own Id: OTP-14977

Fixed a bug where dirty scheduler picked up non-dirty work.

Own Id: OTP-14978

Calls to gen_tcp:send/2 on closed sockets now returns {error, closed} instead of {error,enotconn}.

Own Id: OTP-15001

erlang:monotonic_time/1 failed with badarg when passing the perf_counter time unit as argument.

Own Id: OTP-15008

Fix bug where rapid init:restart() calls would sometimes crash because a code load request leaked in between the restarts.

Own Id: OTP-15013

Improve float_to_list(F, [{decimals,D}]) to closer conform with io_lib:format("~.*f", [D,F]).

There are however, still cases when float_to_list does not produce the exact same result as io_lib:format, especially for large values F and/or many decimals D.

Own Id: OTP-15015 Aux Id: OTP-14890

Fixed a deadlock that would occur on certain allocators when a reallocation failed with +ramv enabled.

Own Id: OTP-15024

Fix bug that made it impossible to use an erl_tracer as the seq_trace trace receiver.

Own Id: OTP-15029

Fix bug where a large (> 1 GB) emulator generated error logger message would cause the emulator to crash.

Own Id: OTP-15032

The emulator will no longer crash when reading the file information of an ordinary file that has an NTFS reparse point, such as files stored in a OneDrive-mapped folder.

Own Id: OTP-15062 Aux Id: ERL-615

Fixed bug in enif_binary_to_term which could cause memory corruption for immediate terms (atoms, small integers, pids, ports, empty lists).

Own Id: OTP-15080

Fixed bug in erlang:system_profile/2 that could cause superfluous {profile,_,active,_,_} messages for terminating processes.

Own Id: OTP-15085

On OSs with per thread CPU time support, change cpu_timestamp in erlang:trace/3 to use it instead of per process CPU time. This makes this option useable on such OSs when running multiple schedulers.

Own Id: OTP-15090

Fix segfault in abort_signal_task which could happen if a port terminated while there were outstanding port tasks that were not signals, for example a ready_input/ready_output event.

Own Id: OTP-15108 Aux Id: ERL-621

Fixed bug in ets that could cause VM crash if process A terminates after fixating a table and process B deletes the table at "the same time". The table fixation could be done with ets:safe_fixtable or if process A terminates in the middle of a long running select or match call.

Own Id: OTP-15109

Owner and group changes through file:write_file_info, file:change_owner, and file:change_group will no longer report success on permission errors.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-15118

Fix a bug error reporting from escripts on windows where the error message would get garbled.

Own Id: OTP-15119 Aux Id: PR-1826

Fix segfault when a process is interally re-scheduled while being traced for in out events. This bug was introduced in erts-8.0 (OTP-19.0).

Own Id: OTP-15125

### Improvements and New Features

It is now possible to open device files and FIFOs with file:open/2.

Own Id: OTP-11462

The erlang:system_flag(scheduler_wall_time,Bool) call is now reference counted and will be turned off if the (last) process that started the performance statistics dies. Thus it is no longer possible to start the statistics with rpc:call(Node, erlang, system_flag, [scheduler_wall_time, true]) since it will be turned off directly afterwards when the rpc process dies.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11694

A new logging API is added to Erlang/OTP, see the logger(3) manual page, and section Logging in the Kernel User's Guide.

Calls to error_logger are automatically redirected to the new API, and legacy error logger event handlers can still be used. It is, however, recommended to use the Logger API directly when writing new code.

Notice the following potential incompatibilities:

Kernel configuration parameters error_logger still works, but is overruled if the default handler's output destination is configured with Kernel configuration parameter logger.

In general, parameters for configuring error logger are overwritten by new parameters for configuring Logger.

The concept of SASL error logging is deprecated, meaning that by default the SASL application does not affect which log events are logged.

By default, supervisor reports and crash reports are logged by the default Logger handler started by Kernel, and end up at the same destination (terminal or file) as other standard log event from Erlang/OTP.

Progress reports are not logged by default, but can be enabled by setting the primary log level to info, for example with the Kernel configuration parameter logger_level.

To obtain backwards compatibility with the SASL error logging functionality from earlier releases, set Kernel configuration parameter logger_sasl_compatible to true. This prevents the default Logger handler from logging any supervisor-, crash-, or progress reports. Instead, SASL adds a separate Logger handler during application start, which takes care of these log events. The SASL configuration parameters sasl_error_logger and sasl_errlog_type specify the destination (terminal or file) and severity level to log for these events.

Since Logger is new in Erlang/OTP 21.0, we do reserve the right to introduce changes to the Logger API and functionality in patches following this release. These changes might or might not be backwards compatible with the initial version.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13295

gen_sctp:connect_init/4 or rather connect in inet_drv.c for SCTP has been fixed to not check the write file descriptor for writeability after a connect, since for SCTP (SOCK_SEQPACKET) that property does not seem to be any kind of indicator for when a connect has finished. This fixes connects that the OS returned as "in progress" that was misinterpreted by gen_sctp:connect_init as failed.

Own Id: OTP-13760 Aux Id: PR-1592

The file driver has been rewritten as a NIF, decreasing the latency of file operations. Notable incompatibilities are:

The use_threads option for file:sendfile/5 no longer has any effect; we either use non-blocking sendfile(2) or fall back to file:read + gen_tcp:send.

The file-specific DTrace probes have been removed. The same effect can be achieved with normal tracing together with the nif__entry/nif__return probes to track scheduling.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14256

The I/O polling functionality of erts has been re-written to better make use of the OSs polling mechanisms. This change means that erts will now always prefer to use a kernel-polling mechanism if possible. Also all of the I/O polling has been moved to dedicated threads instead of being placed in the scheduler loops.

As a result of this, the erl options +K and +secio have been removed. It is still possible to disable kernel-poll, but it has to be done at compile time through the configure option --disable-kernel-poll.

The new erl options +IOt and +IOp can be used to change how many IO poll threads and poll sets that erts should use. See their respective documentation for more details.

Own Id: OTP-14346

Truly asynchronous auto-connect. Earlier, when erlang:send was aimed toward an unconnected node, the function would not return until the connection setup had completed (or failed). Now the function returns directly after the message has been enqueued and the connection setup started.

The same applies to all distributed operations that may trigger auto-connect, i.e. '!', send, link, monitor, monitor_node, exit/2 and group_leader.

The interface for all these functions are unchanged as they do not return connection failures. The only exception is erlang:monitor where a possible incompatibility is introduced: An attempt to monitor a process on a primitive node (such as erl_interface or jinterface), where remote process monitoring is not implemented, will no longer fail with badarg exception. Instead a monitor will be created, but it will only supervise the connection to the node.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14370

Changed the default behaviour of .erlang loading: .erlang is no longer loaded from the current directory. c:erlangrc(PathList) can be used to search and load an .erlang file from user specified directories.

escript, erlc, dialyzer and typer no longer load an .erlang at all.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14439

New functionality for implementation of alternative carriers for the Erlang distribution has been introduced. This mainly consists of support for usage of distribution controller processes (previously only ports could be used as distribution controllers). For more information see ERTS User's Guide ➜ How to implement an Alternative Carrier for the Erlang Distribution ➜ Distribution Module.

Own Id: OTP-14459

Add support for the lcc compiler and in extension the Elbrus 2000 platform.

Own Id: OTP-14492

Support for "tuple calls" have been removed from the run-time system. Tuple calls was an undocumented and unsupported feature which allowed the module argument for an apply operation to be a tuple: Var = dict:new(), Var:size(). This "feature" frequently caused confusion, especially when such call failed. The stacktrace would point out functions that don't exist in the source code.

For legacy code that need to use parameterized modules or tuple calls for some other reason, there is a new compiler option called tuple_calls. When this option is given, the compiler will generate extra code that emulates the old behavior for calls where the module is a variable.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14497

Creation of small maps with literal keys has been optimized to be faster and potentially use less memory. The keys are combined into a literal key tuple which is put into the literal pool. The key tuple can be shared between many instances of maps having the same keys.

Own Id: OTP-14502

When an exception is thrown, include the arguments of the call in the stacktrace for BIFs band, bor, bsl, bsr, bxor, div, rem and the operators +, -, * and /.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14508

The non-smp emulators have been removed. This means that the configure options --disable-threads and --enable-plain-emulator have been removed and configure will now refuse to build Erlang/OTP on platforms without thread support.

In order to achieve a similar setup as the non-smp emulator, it is possible to start Erlang/OTP with the +S 1 option.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14518

Modules that use floating point constants compiled with R15 or earlier will need to be re-compiled before they can be loaded.

Own Id: OTP-14575

Implementation of true asynchronous signaling between processes in order to improve scalability. Signals affected include exit, monitor, demonitor, monitor triggered, link, unlink, and group leader.

Own Id: OTP-14589

Added a PGO (profile guided optimization) pass to the build step of erts. This can be disabled by passing --disable-pgo to configure.

Own Id: OTP-14604

Improved the performance of binary:split and binary:match.

Own Id: OTP-14610 Aux Id: PR-1480

It is not longer possible to disable dirty schedulers when building erlang.

Own Id: OTP-14613

Loaded BEAM code in a 64-bit system requires less memory because of better packing of operands for instructions.

These memory savings were achieved by major improvements to the beam_makeops scripts used when building the run time system and BEAM compiler. There is also new for documentation for beam_makeops that describes how new BEAM instructions and loader transformations can be implemented. The documentation is found in here in a source directory or git repository: erts/emulator/internal_doc/beam_makeops.md. An online version can be found here: https://github.com/erlang/otp/blob/master/erts/emulator/internal_doc/beam_makeops.md

Own Id: OTP-14626

file:read_file has been changed to read the content of files that report a size of 0 even when data can be read from them. An example of such a file is /proc/cpuinfo on Linux.

Own Id: OTP-14637 Aux Id: ERL-327 PR-1524

It is no longer possible to disable the temp_alloc allocator. Disabling it caused serious performance degradations and was never what was wanted.

Own Id: OTP-14651

The reduction cost of sending messages is now constant. It will no longer scale according to the length of the receiving process' message queue.

Own Id: OTP-14667

Improved loading of modules with -on_load directive, to no longer block all schedulers when the load operation is completed.

Own Id: OTP-14680

On platforms with real-time signals available, SIGRTMIN+1 is now used as the internal scheduler suspend signal instead of SIGUSR2.

Own Id: OTP-14682

When the value returned from a 'catch' expression is ignored, no stacktrace will be built if an exception is caught. That will save time and produce less garbage. There are also some minor optimizations of 'try/catch' both in the compiler and run-time system.

Own Id: OTP-14683

The guarantees and non-guarantees of erlang:get_stacktrace/0 are now documented.

Own Id: OTP-14687

There is a new syntax in 'try/catch' for retrieving the stacktrace without calling 'erlang:get_stacktrace/0'. See the reference manual for a description of the new syntax. The 'erlang:get_stacktrace/0' BIF is now deprecated.

Own Id: OTP-14692

New 'used' option for binary_to_term/2 that will also return number of bytes actually read from the binary. This enables easy access to any extra data in the binary located directly after the returned term.

Own Id: OTP-14780

Added more statistics for erlang:system_info({allocator,A}) in the mbcs_pool section.

Own Id: OTP-14795 Aux Id: ERL-88

Added enif_ioq_peek_head to retrieve Erlang terms from NIF IO queues without having to resort to copying.

Own Id: OTP-14797

There is a new option 'makedep_side_effect' for the compiler and -MMD for 'erlc' that generates dependencies and continues to compile as normal.

Own Id: OTP-14830

Added ets:whereis/1 for retrieving the table identifier of a named table.

Own Id: OTP-14884

seq_trace labels may now be any erlang term.

Own Id: OTP-14899

Optimized the common case of monitor followed by send to the same local process. The monitor signal is now delayed in order to be piggybacked with the sent message and thereby only get one lock operation on the message queue of the receiver. A delayed monitor signal is flushed if no send has been done at the latest when the process is scheduled out.

Own Id: OTP-14901

Make hipe compiled code work on x86_64 (amd64) with OS security feature PIE, where executable code can be loaded into a random location. Old behavior, if hipe was enabled, was to disable PIE build options for the VM.

Own Id: OTP-14903

The number of driver async threads will now default to 1 as the standard drivers do not use them anymore. Users that changed this value to tweak the file driver should replace +A with +SDio since it now uses dirty IO schedulers instead of async threads.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14928

Optimize == and /= for binaries with different sizes to be constant in time instead of proportional to the size of their common prefix.

Own Id: OTP-14934 Aux Id: PR-1708

Refactorings making some internal process flags available for other usage.

Own Id: OTP-14948

Removed need for HiPE to allocate native executable memory in low 2GB address space on x86_64. Command line option +MXscs is thereby obsolete and ignored.

Own Id: OTP-14951

Added enif_make_map_from_arrays for creating a populated map, analogous to enif_make_list_from_array.

Own Id: OTP-14954

Added configuration switches for busy-wait and wake up thresholds for dirty schedulers, and changing these settings for normal schedulers will no longer affect dirty schedulers.

Refer to the documentation for details. The new switches are +sbwtdcpu, +sbwtdio, +swtdcpu, and +swtdio.

The default busy wait threshold for dirty scheduler threads has also been lowered to short.

Own Id: OTP-14959

The list of "taints" now also includes dynamic loaded drivers in addition to NIF libraries. Statically linked drivers and NIF libraries that are part of erts are not included. The "taints" are returned by system_info(taints) and printed in the header of erl_crash.dump files.

Own Id: OTP-14960

Added instrument:allocations and instrument:carriers for retrieving information about memory utilization and fragmentation.

The old instrument interface has been removed, as have the related options +Mim and +Mis.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14961

The process suspend functionality used by the erlang:suspend_process/2 BIF has been reimplemented using the newly introduced true asynchronous signaling between processes. This mainly to reduce memory usage in the process control block of all processes, but also in order to simplify the implementation.

You can easily create deadlocks if processes suspends each other (directly or in circles). In ERTS versions prior to ERTS version 10.0, the runtime system prevented such deadlocks, but this prevention has now been removed due to performance reasons.

Other ERTS internal functionality that used the previous process suspend functionality have also been reimplemented to use asynchronous signaling instead.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14964 Aux Id: OTP-14589

Added the nifs option to ?MODULE:module_info/1 for listing a module's installed NIF functions.

Own Id: OTP-14965

New implementation of erlang:process_info/[1,2].

In the general case when inspecting another process, the new implementation sends an asynchronous process-info request signal to the other process and waits for the result instead of locking the other process and reading the result directly. In some special cases where no conflicts occur, signal order wont be violated, and the amount of data requested is guaranteed to be small, the inspected process may be inspected directly.

Appropriate amount of reductions are now also bumped when inspecting a process.

Own Id: OTP-14966

Removed process start time from crash dump in order to save memory in process control block.

Own Id: OTP-14975 Aux Id: PR-1597

Optimize erlang:put/2 when updating existing key with a new immediate value (atom, small integer, pid, port).

Own Id: OTP-14976

erlang:process_info/1 has been changed to no longer include messages by default. Instead erlang:process_info/2 should be used.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14986 Aux Id: PR-1745

New erlang:system_info(ets_count) to get total number of ets tables existing at the local node.

Own Id: OTP-14987

New NIF functions: enif_mutex_name, enif_cond_name, enif_rwlock_name, enif_thread_name, enif_vfprintf, enif_vsnprintf.

Own Id: OTP-14994

When erlang:system_flag(backtrace_depth, 0) has been called, all exceptions will now contain the entry for one function (despite the zero). It used to be that a hand-made stack backtrace passed to erlang:raise/3 would be be truncated to an empty list.

Own Id: OTP-15026

Fixed bug for named ets tables which could cause unexpected results from matchspec iteration functions (ets:select* and ets:match*) if the table was deleted and recreated with the same name during the iteration. The iteration could incorrectly continue through the recreated table. The expected correct behavior is now for the iteration call to fail with a badarg exception if the table is deleted before the iteration has completed.

Own Id: OTP-15031

Two new guards BIFs operating on maps have been added: map_get/2 and is_map_key/2. They do the same as maps:get/2 and maps:is_key/2, respectively, except that they are allowed to be used in guards.

Own Id: OTP-15037 Aux Id: PR-1784, PR-1802

Release run-queue lock while cleaning up terminated dirty process.

Own Id: OTP-15081

The callback module passed as -epmd_module to erl has been expanded to be able to do name and port resolving.

Documentation has also been added in the erl_epmd reference manual and ERTS User's Guide How to Implement an Alternative Node Discovery for Erlang Distribution.

Own Id: OTP-15086 Aux Id: PR-1694

## Erts 9.3.3.15

### Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.

Own Id: OTP-16436 Aux Id: ERL-1152

Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.

Own Id: OTP-16438

A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.

Own Id: OTP-16446 Aux Id: ERL-1157

Fixed erroneous mapping of exit reason from kill to killed on reception of some exit signals due to a broken link. This bug has existed since ERTS version 5.5.2 (OTP R11).

This bug was also unknowingly fixed in ERTS version 10.0 (OTP 21.0) due to a new ERTS internal implementation of signaling between processes.

Own Id: OTP-16465 Aux Id: ERL-1165, OTP-6160, OTP-14589

Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.

Own Id: OTP-16481

## Erts 9.3.3.14

### Fixed Bugs and Malfunctions

A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.

Own Id: OTP-16379

## Erts 9.3.3.13

### Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.

Own Id: OTP-16193

## Erts 9.3.3.12

### Fixed Bugs and Malfunctions

The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.

Own Id: OTP-15867 Aux Id: ERIERL-373

Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.

Own Id: OTP-16058 Aux Id: PR-2382

When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.

Own Id: OTP-16107 Aux Id: ERL-1049

## Erts 9.3.3.11

### Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.

Own Id: OTP-15819 Aux Id: ERL-944

## Erts 9.3.3.10

### Fixed Bugs and Malfunctions

Fixes of install/release phase in build system.

The source tree was modified when installing/releasing and/or applying a patch. Some files were installed with wrong access rights. If applying a patch (using otp_patch_apply) as another user (except root) than the user that built the source, the documentation was not properly updated.

Own Id: OTP-15551

Minor fixes for make clean.

Own Id: OTP-15657

Fixed a bug in all ets:select* and ets:match* functions that could in some rare cases lead to very poor performance.

Own Id: OTP-15660 Aux Id: ERL-869

Fix a possible deadlock when terminating the ERTS caused by a dirty scheduler not releasing it's run-queue lock when terminating.

Own Id: OTP-15690 Aux Id: PR-2172

Add missing documentation of new external tags NEW_PID, NEW_PORT and NEWER_REFERENCE introduced in OTP 19.

These new tags are planned to be "activated" in OTP 23 when distribution capability flag DFLAG_BIG_CREATION becomes mandatory. Older nodes (>= 19) are able to decode these new tags and send them back to the new node. Nodes older than OTP 23 will however never encode their own local pids, ports and references using the new tags.

Own Id: OTP-15766

## Erts 9.3.3.9

### Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation

Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.

Own Id: OTP-15430 Aux Id: ERIERL-237

## Erts 9.3.3.8

### Fixed Bugs and Malfunctions

A bug that could cause dirty schedulers to become unresponsive has been fixed.

Own Id: OTP-15509 Aux Id: PR-2027, PR-2093

## Erts 9.3.3.7

### Fixed Bugs and Malfunctions

Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-15487 Aux Id: ERL-804

## Erts 9.3.3.6

### Improvements and New Features

List subtraction (The -- operator) will now yield properly on large inputs.

Own Id: OTP-15371

## Erts 9.3.3.5

### Fixed Bugs and Malfunctions

ERTS internal trees of monitor structures could get into an inconsistent state. This could cause 'DOWN' messages not to be delivered when they should, as well as delivery of 'DOWN' messages that should not be delivered.

This bug was introduced in ERTS version 9.0 (OTP 20.0) and was fixed in ERTS version 10.0 (OTP 21.0) due to a rewrite of the monitor code. That is, this bug only exist in the OTP 20 release.

Own Id: OTP-15399 Aux Id: ERL-751, ERIERL-262, OTP-14205

## Erts 9.3.3.4

### Fixed Bugs and Malfunctions

Fixed bug in ets:select_replace when called with a fully bound key could cause a following call to ets:next or ets:prev to crash the emulator or return invalid result.

Own Id: OTP-15346

## Erts 9.3.3.3

### Fixed Bugs and Malfunctions

Fixed a bug which caused an emulator crash when enif_send() was called by a NIF that executed on a dirty scheduler. The bug was either triggered when the NIF called enif_send() without a message environment, or when the process executing the NIF was send traced.

Own Id: OTP-15223

Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.

Thanks to Simon Cornish for finding the bug and supplying a fix.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-15225

## Erts 9.3.3.2

### Fixed Bugs and Malfunctions

Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.

Own Id: OTP-15158 Aux Id: ERL-654

Fix bug in generation of erl_crash.dump, which could cause VM to crash.

Bug exist since erts-9.2 (OTP-20.2).

Own Id: OTP-15181

## Erts 9.3.3.1

### Fixed Bugs and Malfunctions

Fixed a rare bug that could cause processes to be scheduled after they had been freed.

Own Id: OTP-15067 Aux Id: ERL-573

## Erts 9.3.3

### Fixed Bugs and Malfunctions

Fixed bug in ets that could cause VM crash if process A terminates after fixating a table and process B deletes the table at "the same time". The table fixation could be done with ets:safe_fixtable or if process A terminates in the middle of a long running select or match call.

Own Id: OTP-15109

## Erts 9.3.2

### Fixed Bugs and Malfunctions

Fixed bug in enif_binary_to_term which could cause memory corruption for immediate terms (atoms, small integers, pids, ports, empty lists).

Own Id: OTP-15080

Fixed bug in erlang:system_profile/2 that could cause superfluous {profile,_,active,_,_} messages for terminating processes.

Own Id: OTP-15085

## Erts 9.3.1

### Fixed Bugs and Malfunctions

Fixed a crash in heart:get_cmd/0 when the stored command was too long.

Own Id: OTP-15034

## Erts 9.3

### Fixed Bugs and Malfunctions

Fixed a configure test for libz internals that unintentionally caused various native code in OTP to link against libz. Under certain circumstances this caused the build of OTP to fail.

Own Id: OTP-14840 Aux Id: ERL-529

File names containing unicode codepoints larger than 255 were not correctly encoded in stack traces.

Own Id: OTP-14847 Aux Id: ERL-544

Fix HiPE bug for binary constructs like <<X/utf8>> which could in rare cases cause faulty results or VM crash.

This fix affects both the hipe compiler and erts runtime in an incompatible way. Old hipe compiled files need to be recompiled to load and run properly as native.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14850 Aux Id: PR-1664

Fix term_to_binary/2 spec for minor_version.

Own Id: OTP-14876 Aux Id: ERL-548

Fix bug in erlang:binary_to_integer/2 where invalid characters were not detected for bases larger then 10. e.g. binary_to_integer(<<":">>, 16) would return 3 and not badarg as it should.

Own Id: OTP-14879

Fixed bug in float_to_list/2 and float_to_binary/2 with option decimals that caused a faulty rounding up of the last decimal digit for about 6% of floats with a fraction part.

For example, float_to_list(0.145, [{decimals,1}]) returned "0.2" instead of "0.1".

Own Id: OTP-14890

Fix bug causing slow hipe execution in modules loaded early during boot or loaded by code:atomic_load or code:finish_loading.

Own Id: OTP-14891

Fixed a buffer overflow in an internal string formatting function that could be hit if specifying a long floating-point format specifier to erts_sprintf or similar.

Own Id: OTP-14920

erlang:iolist_to_iovec/1 and enif_inspect_iovec will no longer fail when provided with binaries that have been matched-out on a non-byte boundary.

Own Id: OTP-14921

iolist_to_binary/1 and erlang:iolist_to_iovec/1 will now badarg if supplied with a bitstring (without a list).

Own Id: OTP-14926

Reject loading modules with names containing directory separators ('/' or '\' on Windows).

Own Id: OTP-14933 Aux Id: ERL-564, PR-1716

Fix potential dead-lock when the tracer process dies while a the traced process is running on a dirty scheduler.

Own Id: OTP-14938

### Improvements and New Features

More crash dump info such as: process binary virtual heap stats, full info for process causing out-of-mem during GC, more port related info, and dirty scheduler info.

Own Id: OTP-14820

## Erts 9.2.1

### Improvements and New Features

Improve search algorithm of abandoned memory carriers. Instead of limited linear search, each allocator instance maintain a balanced search tree of all its abandoned carriers for faster and more exhaustive search.

Own Id: OTP-14915 Aux Id: ERIERL-88

New erts_alloc command line options +M_acnl and +M_acfml to limit carrier abandonment.

Own Id: OTP-14916 Aux Id: ERIERL-88

New family of erts_alloc strategies: Age Order First Fit. Similar to "address order", but instead the oldest possible carrier is always chosen for allocation.

Own Id: OTP-14917 Aux Id: ERIERL-88

Add possibility to change allocator options at runtime with system_info(erts_alloc, ...). Only option sbct (single block carrier threshold) is currently supported via this interface.

Own Id: OTP-14918 Aux Id: ERIERL-88

## Erts 9.2.0.1

### Improvements and New Features

Extra internal consistency checks wrt communication with erl_child_setup process.

Own Id: OTP-15488 Aux Id: ERIERL-231

## Erts 9.2

### Fixed Bugs and Malfunctions

Fix a bug in tracing where the {caller} match spec function would be set to undefined incorrectly when used in conjunction with return_to or return_trace on some functions.

The functions effected are: erlang:put/2, erlang:erase/1, erlang:process_info/1,2, erlang:nif_load/2, erts_internal:garbage_collection/1 and erts_internal:check_process_code/1.

Because of this bug, the analysis done by fprof could become incorrect when the functions above are the tail-call in a function.

Own Id: OTP-14677

Fix emulator deadlock that would happen if trap_exit was set to true and a process sends an exit signal to itself using exit(self(), Reason) while receive tracing was enabled for that process.

Own Id: OTP-14678 Aux Id: ERL-495

Writing of crash dumps is significantly faster.

Maps are now included in crash dumps.

Constants terms would only be shown in one process, while other processes referencing the same constant term would show a marker for incomplete heap.

Own Id: OTP-14685 Aux Id: OTP-14611, OTP-14603, OTP-14595

The fallback home directory for windows has been changed to be the PROFILE directory instead of the WINDOWS directory. The fallback is used when the environment variables HOMEDRIVE and HOMEPATH have not been set.

Own Id: OTP-14691

Fix bug for hipe compiled code using <<X/utf32>> binary construction that could cause faulty result or even VM crash.

On architectures other than x86_64, code need to be recompiled to benefit from this fix.

Own Id: OTP-14740

Fixed bug in erlang:garbage_collect/2 and erlang:check_process_code/3, when called with option {async,ReqestId}. Could cause VM crash or heap corruption if RequestId was an immediate term (like a pid, atom or small integer). Bug exists since OTP-17.0.

Own Id: OTP-14752

ERL_NIF_MINOR_VERSION wasn't bumped with the addition of enif_ioq_*.

Own Id: OTP-14779

Purging of loaded code that contained "fake literals" (for example the magic reference obtained from 'ets:new/2') would crash the runtime system. Corrected.

Own Id: OTP-14791

Setting the size of the atom table to a number near 2147483647 (using the '+t' option) would cause the emulator to exit with a failure to allocate a huge amount of memory. This has been corrected. Also the usage message for the '+t' option has been corrected to show the correct upper limit 2147483647 instead of 0.

Own Id: OTP-14796

Fixed a bug that prevented registered process names from being resolved in lcnt results.

Own Id: OTP-14803

Formatting bugs were fixed in several HiPE debug BIFs.

Own Id: OTP-14804

### Improvements and New Features

Binaries and some other data in crash dumps are now encoded in base64 (instead of in hex), which will reduce the size of crash dumps.

A few bugs in the handling of sub binaries in crashdump_viewer have been fixed.

Own Id: OTP-14686

Micro optimization for send operations of messages to other nodes. The local ack-message, which is otherwise sent back from TPC/IP port driver to sending client process, is now ignored earlier for distributed send operations.

Own Id: OTP-14689

## Erts 9.1.5

### Fixed Bugs and Malfunctions

Fixed a bug in file closure on Unix; close(2) was retried on EINTR which could cause a different (recently opened) file to be closed as well.

Own Id: OTP-14775

A race-condition when tearing down a connection with active node monitors could cause the runtime system to crash.

This bug was introduced in ERTS version 8.0 (OTP 19.0).

Own Id: OTP-14781 Aux Id: OTP-13047

## Erts 9.1.4

### Fixed Bugs and Malfunctions

Microstate accounting sometimes produced incorrect results for dirty schedulers.

Own Id: OTP-14707

Fixed a regression in zlib:gunzip/1 that prevented it from working when the decompressed size was a perfect multiple of 16384. This regression was introduced in 20.1.1

Own Id: OTP-14730 Aux Id: ERL-507

Fixed a memory corruption bug in enif_inspect_iovec; writable binaries stayed writable after entering the iovec.

Own Id: OTP-14745

Fixed a crash in enif_inspect_iovec on encountering empty binaries.

Own Id: OTP-14750

zlib:deflateParams/3 will no longer return buf_error when called after zlib:deflate/2 with zlib 1.2.11.

Own Id: OTP-14751

## Erts 9.1.3

### Fixed Bugs and Malfunctions

Added zlib:set_controlling_process/2 to move a zstream() between processes.

Own Id: OTP-14672 Aux Id: ERL-494

Fix so that schedulers are bound correctly when the first available cpu is not the first detected cpu. e.g. when using "taskset -c X..Y" when X is not equal to 0.

Own Id: OTP-14694

## Erts 9.1.2

### Fixed Bugs and Malfunctions

Fixed bug that could cause a VM crash when a corrupt message is received on distribution channel from other node.

Own Id: OTP-14661 Aux Id: ERIERL-80

## Erts 9.1.1

### Fixed Bugs and Malfunctions

The new zlib module returned a data_error when inflating concatenated streams, which was incompatible with the old module's behavior of returning the uncompressed data up to the end of the first stream.

Own Id: OTP-14648

zlib:gunzip/1 will no longer stop at the end of the first stream when decompressing concatenated gzip files.

Own Id: OTP-14649

## Erts 9.1

### Fixed Bugs and Malfunctions

Changed erlang:apply/2 to raise a badarg exception if the second argument is not a proper list. Previous behavior was a misleading undef exception.

Own Id: OTP-14490 Aux Id: ERL-432

On macOS, crypto would crash if observer had been started before crypto. On the beta for macOS 10.13 (High Sierra), crypto would crash. Both of those bugs have been fixed.

Own Id: OTP-14499 Aux Id: ERL-251 ERL-439

Fixed bug in enif_whereis_pid/port that could cause heap corruption in rare cases.

Own Id: OTP-14523

Fix so that trace messages generated when in a dirty nif are flushed correctly when the dirty nif is done executing.

Own Id: OTP-14538

Fix escape code handling when using ANSI color codes in the shell.

Own Id: OTP-14549 Aux Id: PR1536

Upgraded the ERTS internal PCRE library from version 8.40 to version 8.41. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.

Own Id: OTP-14574

Fixed a bug causing statistics(runtime) to produce negative values and a bug in statistics(wall_clock) causing it to produce values one second too long.

statistics(runtime) now also use getrusage() as source when available preventing the returned value from wrapping as frequent as before.

Own Id: OTP-14597 Aux Id: ERL-465

Fixed small memory leak that could occur when sending to a terminating port.

Own Id: OTP-14609

Fix bug causing VM crash when a module with -on_load directive is loaded while erlang:trace(on_load, ...) is enabled.

Own Id: OTP-14612

A warning that the compiler may optimize away atoms have been added to the documentation of list_to_existing_atom/1 and binary_to_existing_atom/2.

Own Id: OTP-14614 Aux Id: ERL-453

### Improvements and New Features

Lock counting can now be fully toggled at runtime in the lock counting emulator (-emu_type lcnt). Everything is enabled by default to match the old behavior, but specific categories can be toggled at will with minimal runtime overhead when disabled. Refer to the documentation on lcnt:rt_mask/1 for details.

Own Id: OTP-13170

The zlib module has been refactored and all its operations will now yield appropriately, allowing them to be used freely in concurrent applications.

The following functions have been deprecated, but will not produce compiler warnings until OTP 21: zlib:adler32, zlib:crc32, zlib:inflateChunk, zlib:getBufSize, zlib:setBufSize.

The behavior of throwing an error when a dictionary is required for decompression has also been deprecated. Refer to the documentation on inflateSetDictionary/2 for details.

Own Id: OTP-14185

lcnt:collect and lcnt:clear will no longer block all other threads in the runtime system.

Own Id: OTP-14412

Add erlang:iolist_to_iovec/1, which converts an iolist() to an erlang:iovec(), which suitable for use with enif_inspect_iovec.

Own Id: OTP-14520

When provided with bad arguments, the zlib module will now raise named exceptions instead of just badarg. For example, not_initialized when using zlib:inflate/2 with an uninitialized stream.

Own Id: OTP-14527

erlang:halt/2 allows any Unicode string as slogan for the crash dump.

Own Id: OTP-14553

Add new nif API functions for managing an I/O Queue. The added functions are:

enif_ioq_create() enif_ioq_destroy() enif_ioq_enq_binary() enif_ioq_enqv() enif_ioq_deq() enif_ioq_peek() enif_inspect_iovec() enif_free_iovec()

Own Id: OTP-14598

## Erts 9.0.5

### Fixed Bugs and Malfunctions

Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).

Own Id: OTP-14590 Aux Id: ERL-474

## Erts 9.0.4

### Fixed Bugs and Malfunctions

A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.

This bug was introduced in ERTS version 7.0 (OTP 18.0).

Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468

Automatic cleanup of a BIF timer, when the owner process terminated, could race with the timeout of the timer. This could cause the VM internal data structures to become inconsistent which very likely caused a VM crash.

This bug was introduced in ERTS version 9.0 (OTP 20.0).

Own Id: OTP-14554 Aux Id: OTP-14356, ERL-468

## Erts 9.0.3

### Fixed Bugs and Malfunctions

Binary append operations did not check for overflow, resulting in nonsensical results when huge binaries were appended.

Own Id: OTP-14524

## Erts 9.0.2

### Fixed Bugs and Malfunctions

Added missing release notes for OTP-14491 ("performance bug in pre-allocators") which was included in erts-9.0.1 (OTP-20.0.1).

Own Id: OTP-14494

Fixed a bug that prevented TCP sockets from being closed properly on send timeouts.

Own Id: OTP-14509

Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-14514

## Erts 9.0.1

### Fixed Bugs and Malfunctions

Fixed a bug in gen_tcp:send where it never returned when repeatedly called on a remotely closed TCP socket.

Own Id: OTP-13939 Aux Id: ERL-193

Fixed segfault that could happen during cleanup of aborted erlang:port_command/3 calls. A port_command is aborted if the port is closed at the same time as the port_command was issued. This bug was introduced in erts-8.0.

Own Id: OTP-14481

Fixed implementation of statistics(wall_clock) and statistics(runtime) so that values do not unnecessarily wrap due to the emulator. Note that the values returned by statistics(runtime) may still wrap due to limitations in the underlying functionality provided by the operating system.

Own Id: OTP-14484

Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02. [this release note was missing in erts-9.0.1]

Own Id: OTP-14491

## Erts 9.0

### Fixed Bugs and Malfunctions

Fix various bugs regarding loading, upgrade and purge of HiPE compiled code:

The native code memory for a purged module was never deallocated. Wrong functions could in some cases be called after a module upgrade. erlang:check_process_code did not check for recursive calls made from native code.

Own Id: OTP-13968

Hipe optional LLVM backend does require LLVM version 3.9 or later as older versions forced strong dependencies on erts internals structures.

Own Id: OTP-14238

When an exception such as 'throw(HugeTerm)' was caught, HugeTerm term would be kept in the process until the next exception occurred, potentially increasing the heap size for the process. That has been corrected.

Own Id: OTP-14255 Aux Id: OTP-14400, OTP-14401

Slogans in crash dumps have been extended to print more complex terms.

Own Id: OTP-14303

Fixed bug when using enif_inspect_binary in combination with enif_copy. In some circumstances the inspected binary could be reallocated by the enif_copy call when it shouldn't have been.

Own Id: OTP-14304

The address family local (AF_UNIX / AF_LOCAL) now does not ensure zero termination of Linux Abstract Addresses so they can use all bytes.

Own Id: OTP-14305

Use -fno-PIE for Gentoo Hardened and others that don't accept linker flag -no-pie.

Own Id: OTP-14307 Aux Id: PR-1379

Disable hipe for ppc64le architecture (little endian) as it is not, and has never been, supported. It was earlier equated with ppc64 (big endian) which lead to broken build without --disable-hipe.

Own Id: OTP-14314 Aux Id: ERL-369, PR-1394

Fix 'epmd -kill' to return a failure exit status code if epmd was not killed because of some error.

Own Id: OTP-14324

Fixed the following dirty scheduler related bugs:

the +SDPcpu command line argument could cause the amount of dirty CPU schedulers to be set to zero

erlang:system_flag(multi_scheduling, _) failed when only one normal scheduler was used together with dirty scheduler support

Own Id: OTP-14335

Fix erlexec to handle mismatch in sysconf and proc fs when figuring out the cpu topology. This behaviour has been seen when using docker together with --cpuset-cpus.

Own Id: OTP-14352

Fixed memory segment cache used for multiblock carriers. Huge (> 2GB) memory segments could cause a VM crash. Creation of such huge memory segments used for multiblock carriers is however very uncommon.

Own Id: OTP-14360 Aux Id: ERL-401, PR-1417

Fix bug causing code:is_module_native to falsely return true when local call trace is enabled for the module.

Own Id: OTP-14390

Fix emulator crash when receive tracing on a trace_delivered message.

Own Id: OTP-14411

Fix file:sendfile error handling on SunOS when a connection is closed during transmission.

Own Id: OTP-14424

escript did not handle paths with spaces correct.

Own Id: OTP-14433

Fix erroneous lock check assertion when wx is run on MacOS X.

Own Id: OTP-14437 Aux Id: ERL-360

Active-mode TCP sockets are now cleaned up properly on send/shutdown errors.

Own Id: OTP-14441 Aux Id: ERL-430

Fix compilation of hipe_mkliterals when the LIBS configure variable had to be set.

Own Id: OTP-14447

### Improvements and New Features

Added erlang:garbage_collect/2 that takes an option list as the last argument that can be used to control whether a minor or a major garbage collection is to be done. Doing a minor collection only collects terms that have recently died, but is cheaper than a major collection.

Own Id: OTP-11695

Optimized test for tuples with an atom as first element.

Own Id: OTP-12148

Erlang literals are no longer copied during process to process messaging.

Own Id: OTP-13529

Add support in the erl_nif API for asynchronous message notifications when sockets or other file descriptors are ready to accept read or write operations. The following functions have been added:

enif_select

enif_monitor_process

enif_demonitor_process

enif_compare_monitors

enif_open_resource_type_x

Own Id: OTP-13684

There are two new guard BIFs 'floor/1' and 'ceil/1'. They both return integers. In the 'math' module, there are two new BIFs with the same names that return floating point values.

Own Id: OTP-13692

Remove deprecated erlang:hash/2.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13827

Replaced usage of deprecated symbolic time unit representations.

Own Id: OTP-13831 Aux Id: OTP-13735

Added support in zlib for extraction of the inflation dictionary.

Own Id: OTP-13842

The previously used purge strategy has been removed. The optional purge strategy introduced in ERTS version 8.1 is now the only strategy available.

The new purge strategy is slightly incompatible with the old strategy. Previously processes holding funs that referred to the module being purged either failed a soft purge, or was killed during a hard purge. The new strategy completely ignores funs. If funs referring to the code being purged exist, and are used after a purge, an exception will be raised upon usage. That is, the behavior will be exactly the same as the case when a fun is received by a process after the purge.

For more information see the documentation of erlang:check_process_code/3.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13844 Aux Id: OTP-13833

Dirty schedulers are now enabled by default when the runtime system is built with SMP support.

Own Id: OTP-13860

Improved ETS lookup/insert/delete speed for large set, bag and duplicate_bag by a significant reduction of the hash load factor. This speed improvement comes at the expense of less than one word per table entry. Tables with less than 256 entries are not affected at all.

Own Id: OTP-13903

The NIF library reload feature is not supported anymore. It has been marked as deprecated since OTP R15B. This means that you are only allowed to do one successful call to erlang:load_nif/2 for each module instance. A second call to erlang:load_nif/2 will return {error, {reload, _}} even if the NIF library implements the reload callback.

Runtime upgrade of a NIF library is still supported by using the Erlang module upgrade mechanics with a current and an old module instance existing at the same time with their corresponding NIF libraries.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13908

Add erlang:system_info(atom_count) and erlang:system_info(atom_limit) to provide a way to retrieve the current and maximum number of atoms.

Own Id: OTP-13976

The function fmod/2 has been added to the math module.

Own Id: OTP-14000

erlang:load_nif/2 returns new error type notsup when called for a HiPE compiled module, which is not supported.

Own Id: OTP-14002

Add driver and nif lock instrumentation to lcnt

Own Id: OTP-14069

Reduce memory pressure by converting sub-binaries to heap-binaries when possible. This is done during garbage collection.

Own Id: OTP-14149

Dirty schedulers are now enabled and supported on Erlang runtime systems with SMP support.

Besides support for dirty NIFs also support for dirty BIFs and dirty garbage collection have been introduced. All garbage collections that potentially will take a long time to complete are now performed on dirty schedulers if enabled.

erlang:statistics/1 with arguments inspecting scheduler and run queue states have been changed due to the dirty scheduler support. Code using this functionality may have to be rewritten taking these incompatibilities into consideration. Examples of such uses are calls to erlang:statistics(scheduler_wall_time), statistics(total_run_queue_lengths), statistics(total_active_tasks), etc.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14152

Atoms may now contain arbitrary Unicode characters.

Own Id: OTP-14178

Introduce an event manager in Erlang to handle OS signals. A subset of OS signals may be subscribed to and those are described in the Kernel application.

Own Id: OTP-14186

The escript program now handles symbolic links to escripts.

This is useful for standalone systems with escripts residing on a bin directory not included in the execution path (as it may cause their erl program(s) to override the desired one). Instead the escripts can be referred to via symbolic links from a bin directory in the path.

Own Id: OTP-14201 Aux Id: PR-1293

All uses of the magic binary kludge has been replaced by uses of erlang references.

A magic binary was presented as an empty binary, but actually referred other data internally in the Erlang VM. Since they were presented as empty binaries, different magic binaries compared as equal, and also lost their internal data when passed out of an erlang node.

The new usage of references has not got any of these strange semantic issues, and the usage of these references has been optimized to give the same performance benefits as well as memory usage benefits as magic binaries had.

A couple of examples of previous uses of magic binaries are match specifications and NIF resources.

Own Id: OTP-14205

The non-smp emulators have been deprecated and are scheduled for removal in OTP-21.

In preparation for this, the threaded non-smp emulator is no longer built by default and has to be enabled using the --enable-plain-emulator to configure.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14272

Allow HiPE to run on VM built with --enable-m32-build.

Own Id: OTP-14330 Aux Id: PR-1397

Upgraded the OTP internal PCRE library from version 8.33 to version 8.40. This library is used for implementation of the re regular expressions module.

Besides various bug fixes, the new version allows for better stack protection. In order to utilize this feature, the stack size of normal scheduler threads is now by default set to 128 kilo words on all platforms. The stack size of normal scheduler threads can be set upon system start by passing the +sss command line argument to the erl command.

See http://pcre.org/original/changelog.txt for information about changes made to PCRE between the versions 8.33 and 8.40.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14331 Aux Id: ERL-208

Remove generation of atoms in old latin1 external format in the distribution between erlang nodes, erl_interface, and jinterface. The new utf8 format for atoms was introduced in OTP R16. An OTP 20 node can therefore not connect to nodes older than R16.

Atoms that can be encoded using latin1 are still encoded by term_to_binary() using latin1 encoding. Note that all atoms will by default be encoded using utf8 in a future Erlang/OTP release. For more information see the documentation of erlang:term_to_binary/2.

Own Id: OTP-14337

Added function re:version/0 which returns information about the OTP internal PCRE version used for implementation of the re module.

Own Id: OTP-14347 Aux Id: PR-1412

Added new debug bif erlang:list_to_port/1.

Own Id: OTP-14348

Various improvements of timer management internally in the VM. These improvements both reduced memory consumption of timer wheels as well as reduce the amount of work that has to be performed in order to handle timers.

Own Id: OTP-14356

Sockets can now be bound to device (SO_BINDTODEVICE) on platforms where it is supported.

This has been implemented e.g to support VRF-Lite under Linux; see VRF , and GitHub pull request #1326.

Own Id: OTP-14357 Aux Id: PR-1326

Added the following erl command line arguments with which you can set suggested stack for dirty schedulers:

+sssdcpu

for dirty CPU schedulers

+sssdio

for dirty IO schedulers

The default suggested stack size for dirty schedulers is 40 kilo words.

Own Id: OTP-14380

Changed erts startup program name, argv 0, to use the environment variable ESCRIPT_NAME so that erlc, dialyzer, typer, ct_run, or the escript name can be seen with external programs, such as ps and htop (depending on options), on unix.

Own Id: OTP-14381

Improvements of escript documentation.

Own Id: OTP-14384 Aux Id: OTP-14201

Add function enif_hash for NIFs to calculate hash values of arbitrary terms.

Own Id: OTP-14385 Aux Id: PR-1413

'./configure --enable-lock-counter' will enabling building of an additional emulator that has support for lock counting. (The option previously existed, but would turn on lock counting in the default emulator being built.) To start the lock-counting emulator, use 'erl -emu_type lcnt'.

On Windows, erl recognized the undocumented option -debug for starting a debug-compiled emulator. That option has been removed. Use 'erl -emu_type debug' instead.

Own Id: OTP-14407

Warnings have been added to the relevant documentation about not using un-secure distributed nodes in exposed environments.

Own Id: OTP-14425

Improvement of the documentation of the environment variable ERL_CRASH_DUMP_SECONDS as well as the default behavior when it is not set.

Own Id: OTP-14434

Enabled off-heap message queue for some system processes that might receive large amounts of messages.

Own Id: OTP-14438

ETS lock indexes have been replaced with the table name in LCNT results.

Own Id: OTP-14442 Aux Id: ERIERL-22

Introduced the new functions enif_whereis_pid() and enif_whereis_port().

Own Id: OTP-14453 Aux Id: PR-1400

## Erts 8.3.5.7

### Fixed Bugs and Malfunctions

Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-15487 Aux Id: ERL-804

### Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation

Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.

Own Id: OTP-15430 Aux Id: ERIERL-237

## Erts 8.3.5.6

### Fixed Bugs and Malfunctions

Fixed small memory leak that could occur when sending to a terminating port.

Own Id: OTP-14609 Aux Id: ERIERL-238

## Erts 8.3.5.5

### Fixed Bugs and Malfunctions

Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.

Own Id: OTP-15158 Aux Id: ERL-654

Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.

Thanks to Simon Cornish for finding the bug and supplying a fix.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-15225

## Erts 8.3.5.4

### Fixed Bugs and Malfunctions

Fixed a bug in file closure on Unix; close(2) was retried on EINTR which could cause a different (recently opened) file to be closed as well.

Own Id: OTP-14775

A race-condition when tearing down a connection with active node monitors could cause the runtime system to crash.

This bug was introduced in ERTS version 8.0 (OTP 19.0).

Own Id: OTP-14781 Aux Id: OTP-13047

## Erts 8.3.5.3

### Fixed Bugs and Malfunctions

A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.

This bug was introduced in ERTS version 7.0 (OTP 18.0).

Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468

Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).

Own Id: OTP-14590 Aux Id: ERL-474

Fix bug causing VM crash when a module with -on_load directive is loaded while erlang:trace(on_load, ...) is enabled.

Own Id: OTP-14612

Fixed bug that could cause a VM crash when a corrupt message is received on distribution channel from other node.

Own Id: OTP-14661 Aux Id: ERIERL-80

## Erts 8.3.5.2

### Fixed Bugs and Malfunctions

Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02.

Own Id: OTP-14491

Fixed a bug that prevented TCP sockets from being closed properly on send timeouts.

Own Id: OTP-14509

Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-14514

## Erts 8.3.5.1

### Fixed Bugs and Malfunctions

Fixed a bug in gen_tcp:send where it never returned when repeatedly called on a remotely closed TCP socket.

Own Id: OTP-13939 Aux Id: ERL-193

Fixed segfault that could happen during cleanup of aborted erlang:port_command/3 calls. A port_command is aborted if the port is closed at the same time as the port_command was issued. This bug was introduced in erts-8.0.

Own Id: OTP-14481

Fixed implementation of statistics(wall_clock) and statistics(runtime) so that values do not unnecessarily wrap due to the emulator. Note that the values returned by statistics(runtime) may still wrap due to limitations in the underlying functionality provided by the operating system.

Own Id: OTP-14484

## Erts 8.3.5

### Fixed Bugs and Malfunctions

Active-mode TCP sockets are now cleaned up properly on send/shutdown errors.

Own Id: OTP-14441 Aux Id: ERL-430

A code purge operation could under certain circumstances expand the size of hibernated processes.

Own Id: OTP-14444 Aux Id: ERIERL-24

Fix so that the ERL_ZZ_SIGTERM_KILL introduced in erts-8.3.4 works.

Own Id: OTP-14451

## Erts 8.3.4

### Fixed Bugs and Malfunctions

Add option to make SIGTERM trigger the OS default behaviour instead of doing a gracefull shutdown. To activate this bahviour the environment variable ERL_ZZ_SIGTERM_KILL should be set to "true". This option only works in OTP 19 as OTP 20 will have a different way to deal with SIGTERM.

Own Id: OTP-14418 Aux Id: ERIERL-15

## Erts 8.3.3

### Fixed Bugs and Malfunctions

Fixed memory segment cache used for multiblock carriers. Huge (> 2GB) memory segments could cause a VM crash. Creation of such huge memory segments used for multiblock carriers is however very uncommon.

Own Id: OTP-14360 Aux Id: ERL-401, PR-1417

Fix release note for OTP-14290 in ERTS version 8.3.1. It was erroneously placed under "Known Bugs and Problems".

Own Id: OTP-14363 Aux Id: OTP-14290

## Erts 8.3.2

### Fixed Bugs and Malfunctions

The +Bi command line argument of erl erroneously caused SIGTERM to be ignored by the VM as well as of all its child processes. This bug was introduced in erts version 8.3.

Own Id: OTP-14358 Aux Id: OTP-14085

## Erts 8.3.1

### Fixed Bugs and Malfunctions

Invoking init:stop/0 via the SIGTERM signal, in a non-SMP BEAM, could cause BEAM to terminate with fatal error. This has now been fixed and the BEAM will terminate normally when SIGTERM is received.

Own Id: OTP-14290

Trying to open a directory with file:read_file/1 on Unix leaked a file descriptor. This bug has now been fixed.

Own Id: OTP-14308 Aux Id: ERL-383

## Erts 8.3

### Fixed Bugs and Malfunctions

Fixed a number of bugs that caused faulty stack-traces to be generated. The faulty stack traces were generated either when applying the following functions or tracing the following functions:

erlang:error/1 erlang:error/2 erlang:exit/1 erlang:throw/1

Own Id: OTP-14055

Corrected documentation about memory footprint for maps.

Own Id: OTP-14118

Fix process_info(Pid, current_stacktrace) to use stack depth limit set by system_flag(backtrace_depth). The old behavior was a hard coded depth limit of 8.

Own Id: OTP-14119 Aux Id: PR-1263

A process calling erlang:system_flag(multi_scheduling, block) could end up hanging forever in the call.

Own Id: OTP-14121

Dirty scheduler bug fixes:

Fixed call time tracing of process being scheduled on dirty scheduler.

GC info from dirty schedulers.

Multi scheduling block with dirty schedulers could crash the runtime system.

Process structures could be removed prematurely.

GC on dirty scheduler could crash the runtime system.

Termination of a process executing on a dirty scheduler could cause a runtime system crash.

Own Id: OTP-14122

Fixed crash that occurred when writing timer data to a crash dump.

Own Id: OTP-14133

A literal area could be removed while still referred from processes.

Own Id: OTP-14134

Fixed a bug in the garbage collector that could crash the runtime system.

Own Id: OTP-14135

Fixed a bug in call-time trace for NIFs which caused tracing to erroneously be started multiple times for one call.

Own Id: OTP-14136

Remove a debug printout and an unnecessary garbage collection when handling exceptions in hipe compiled code.

Own Id: OTP-14153

Fix bug in tracing of garbage collection that could cause VM crash. Bug exists since OTP 19.0.

Own Id: OTP-14154

Fix bug in binary_to_term for binaries created by term_to_binary with option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.

Own Id: OTP-14159 Aux Id: ERL-340

Fix suspension of schedulers when generating a crashdump.

Own Id: OTP-14164

NIF resources was not handled in a thread-safe manner in the runtime system without SMP support.

As a consequence of this fix, the following driver functions are now thread-safe also in the runtime system without SMP support:

driver_free_binary()

driver_realloc_binary()

driver_binary_get_refc()

driver_binary_inc_refc()

driver_binary_dec_refc()

Own Id: OTP-14202

Fix erlang:round/1 for large floating point numbers with an odd absolute value between (1 bsl 52) and (1 bsl 53). The result was falsely calculated as the next higher even number even though all integer values up to (1 bsl 53) can be represented as floats with full precision.

Own Id: OTP-14227

Add size of literals to module code size in crash dump and (l)oaded command in break menu like it used to be before OTP-19.0.

Own Id: OTP-14228

Fix potential bug in enif_send when called without a process context and with argument msg_env as NULL.

Own Id: OTP-14229

Fix bug where passing an appendable binary to erlang:port_control() could crash the emulator.

Own Id: OTP-14231

Receive expressions with timeout in the Erlang shell could cause a VM crash.

Own Id: OTP-14241 Aux Id: ERL-365

### Improvements and New Features

A received SIGTERM signal to beam will generate a 'stop' message to the init process and terminate the Erlang VM nicely. This is equivalent to calling init:stop/0.

Own Id: OTP-14085

Workaround for buggy Android implementation of PTHREAD_STACK_MIN causing build of runtime system to crash on undeclared PAGE_SIZE.

Own Id: OTP-14165 Aux Id: ERL-319

Add configure option --without-thread-names that removes the naming of individual emulator threads.

Own Id: OTP-14234

Add warning in documentation of zlib:deflateInit/6 about option WindowsBits values 8 and -8.

Own Id: OTP-14254 Aux Id: ERL-362

## Erts 8.2.2

### Fixed Bugs and Malfunctions

Fix bug in binary_to_term for binaries created by term_to_binary with option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.

Own Id: OTP-14159 Aux Id: ERL-340

The driver efile_drv when opening a file now use fstat() on the open file instead of stat() before opening, if fstat() exists. This avoids a race when the file happens to change between stat() and open().

Own Id: OTP-14184 Aux Id: seq-13266

## Erts 8.2.1

### Fixed Bugs and Malfunctions

Fix a quite rare bug causing VM crash during code loading and the use of export funs (fun M:F/A) of not yet loaded modules. Requires a very specfic timing of concurrent scheduler threads. Has been seen on ARM but can probably also occure on other architectures. Bug has existed since OTP R16.

Own Id: OTP-14144 Aux Id: seq13242

## Erts 8.2

### Fixed Bugs and Malfunctions

Fixed configure failures on MacOSX. Most important clock_gettime() was detected when building for MacOSX - El Capitan using XCode 8 despite it is not available until MacOSX - Sierra.

Own Id: OTP-13904 Aux Id: ERL-256

code:add_pathsa/1 and command line option -pa both revert the given list of directories when adding it at the beginning of the code path. This is now documented.

Own Id: OTP-13920 Aux Id: ERL-267

Fix a compilation error of erts in OpenBSD related to the usage of the __errno variable.

Own Id: OTP-13927

Fixed so that when enabling tracing on a process that had an invalid tracer associated with it, the new tracer overwrites the old tracer. Before this fix, calling erlang:trace/3 would behave as if the tracer was still alive and not apply the new trace.

This fault was introduced in ERTS 8.0.

Own Id: OTP-13928

Fix parsing of -profile_boot 'true' | 'false'

Own Id: OTP-13955 Aux Id: ERL-280

A slight improvement of erlang:get_stacktrace/0 for exceptions raised in hipe compiled code. Beam compiled functions in such stack trace was earlier replaced by some unrelated function. They are now instead omitted. This is an attempt to reduce the confusion in the absence of a complete and correct stack trace for mixed beam and hipe functions.

Own Id: OTP-13992

Correct type declaration of match specification head.

Own Id: OTP-13996

HiPE code loading failed for x86_64 if gcc was configured with --enable-default-pie. Fixed by disabling PIE, if needed for HiPE, when building the VM.

Own Id: OTP-14031 Aux Id: ERL-294, PR-1239

Faulty arguments could be presented on exception from a NIF that had rescheduled itself using enif_schedule_nif().

Own Id: OTP-14048

The runtime system could crash if a garbage collection on a process was performed immediately after a NIF had been rescheduled using enif_schedule_nif().

Own Id: OTP-14049

A reference to purged code could be left undetected by the purge operation if a process just had rescheduled a NIF call using enif_schedule_nif() when the process was checked. This could cause a runtime system crash.

Own Id: OTP-14050

Fixed a number of dirty scheduler related bugs:

Process priority was not handled correct when scheduling on a dirty scheduler.

The runtime system could crash when an exit signal with a compound exit reason was sent to a process executing on a dirty scheduler.

The runtime system crashed when call tracing a process executing on a dirty scheduler.

A code purge operation could end up hanging forever when a process executed on a dirty scheduler

Own Id: OTP-14051

### Improvements and New Features

Fix minor soft purge race bug that could incorrectly trigger code_server to load new code for the module if the soft purge failed and no current version of the module existed.

Own Id: OTP-13925

To ease troubleshooting, erlang:load_nif/2 now includes the return value from a failed call to load/reload/upgrade in the text part of the error tuple. The crypto NIF makes use of this feature by returning the source line where/if the initialization fails.

Own Id: OTP-13951

New environment variable ERL_CRASH_DUMP_BYTES can be used to limit the size of crash dumps. If the limit is reached, crash dump generation is aborted and the generated file will be truncated.

Own Id: OTP-14046

## Erts 8.1.1.1

### Fixed Bugs and Malfunctions

A code purge operation could under certain circumstances expand the size of hibernated processes.

Own Id: OTP-14444 Aux Id: ERIERL-24

## Erts 8.1.1

### Fixed Bugs and Malfunctions

The emulator got a dynamic library dependency towards libsctp, which on Linux was not intended since the emulator there loads and resolves the needed sctp functions in runtime. This has been fixed and a configure switch --enable-sctp=lib has been added for those who want such a library dependency.

Own Id: OTP-13956 Aux Id: ERL-262, ERL-133

Fix SIGUSR1 crashdump generation

Do not generate a core when a crashdump is asked for.

Own Id: OTP-13997

The new functions in code that allows loading of many modules at once had a performance problem. While executing a helper function in the erl_prim_loader process, garbage messages were produced. The garbages messages were ignored and ultimately discarded, but there would be a negative impact on performance and memory usage. The number of garbage message depended on both the number of modules to be loaded and the length of the code path.

The functions affected of this problem were: atomic_load/1, ensure_modules_loaded/1, and prepare_loading/1.

Own Id: OTP-14009

## Erts 8.1

### Fixed Bugs and Malfunctions

Fix bug for calls from hipe code to BIFs that disable GC while yielding. Has been causing Dialyzer crashes on ARM (and presumably all other non-intel platforms).

Own Id: OTP-13724 Aux Id: PR-1116

Fix a bug where changing the current working directory of the VM would not change the current working directory of programs spawned using erlang:open_port({spawn,""}, ...).

Own Id: OTP-13733 Aux Id: ERL-175

Fix a bug where disabling tracing from a process that had return_to tracing enabled and was tracing on erlang:trace/3 would cause a segmentation fault.

Own Id: OTP-13734

Update all erts documentation to use simpler English, use consistent terminology and be easier to navigate.

Own Id: OTP-13740

Add dirty schedulers to the microstate accounting statistics.

Own Id: OTP-13744

Fixed dirty scheduler build support on 32-bit windows.

Own Id: OTP-13759

inet:getstat(Socket) on an SCTP socket returned 0 for send stats. This bug has now been corrected. Reported by systra as issue ERL-102 on bugs.erlang.org.

Own Id: OTP-13773 Aux Id: ERL-102

AF_UNSPEC and unknown address families were misread by UDP receive in prim_inet resulting in an exception. This bug has now been corrected.

Own Id: OTP-13775

Sweep HiPE stack for literals during code purge.

Own Id: OTP-13777 Aux Id: PR-1122

Fix bug in run_erl for OpenBSD that could cause it on rare occations to exit without starting the program (erl) at all.

Own Id: OTP-13795

Update build scripts to not make assumtions about where env, cp and perl are located.

Own Id: OTP-13800

Fixed a bug where init:stop could deadlock if a process with infinite shutdown timeout (e.g. a supervisor) attempted to load code while terminating.

Own Id: OTP-13802

Fixed a segmentation fault on sparc CPUs when free'ing a tracer module's state.

Own Id: OTP-13803

funs was not properly handled during purge of a module. This could cause a crash of the VM after a purge of a module.

Own Id: OTP-13809

Fixed a memory leak when the process monitoring a port crashed.

Own Id: OTP-13818

Fixed multiple dirty scheduler related tracing bugs.

Own Id: OTP-13822

Fix error handling in beam code runtime loader for a number of cases when index and size fields got corrupted (negative) values.

Own Id: OTP-13848 Aux Id: ERL-216

Minor fix of dirty scheduler implementation.

Own Id: OTP-13852

Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.

Own Id: OTP-13866

Fix a rare race condition in erlang:open_port({spawn, ""}, ...) that would result in the erl_child_setup program aborting and cause the emulator to exit.

Own Id: OTP-13868

Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:

erl_drv_send_term() driver_send_term() erl_drv_output_term() driver_output_term() enif_send() enif_port_command()

Own Id: OTP-13869

Fix start scripts generation dependency in Makefile

Own Id: OTP-13871 Aux Id: ERL-241

The VM could crash if erlang:get_stacktrace() was called after a rescheduled NIF had thrown an exception.

Own Id: OTP-13877

Calling code:delete/1 before a loading a module with an on_load function, the old code would be overwritten, causing a memory or a crash if NIFs were involved. (Thanks to vans163 for reporting this bug.)

Own Id: OTP-13893 Aux Id: ERL-240

### Improvements and New Features

Improved accuracy of timeouts on MacOS X. This by setting premature timeouts followed by a short actual timeout during scheduler wait.

Own Id: OTP-13698

Added the following symbolic time unit representations to the erlang:time_unit() type:

second millisecond microsecond nanosecond

The following symbolic time unit representations are now deprecated, but still part of the erlang:time_unit() type:

seconds milli_seconds micro_seconds nano_seconds

Own Id: OTP-13735

Fix maps hashing entropy of maps with maps keys.

Own Id: OTP-13763 Aux Id: ERL-199

Improved dirty scheduler support. A purge of a module can now be performed without having to wait for completion of all ongoing dirty NIF calls.

Note that when enabling support for dirty schedulers, a new purge strategy will as of ERTS version 8.1 be enabled. This new strategy is not fully backwards compatible with the strategy used by default. For more information see the documentation of erlang:check_process_code/3.

Own Id: OTP-13808 Aux Id: OTP-13833

A new purge strategy has been introduced. The new strategy will by default be disabled during the OTP 19 release, but will be the only strategy available as of the OTP 20 release.

The new strategy is slightly incompatible with the strategy being used by default in OTP 19. Using the default strategy, processes holding funs that refer to the module being purged either fail a soft purge, or will be killed during a hard purge. The new strategy completely ignores funs. If funs referring to the code being purged exist, and are used after a purge, an exception will be raised upon usage. That is, the behavior will be exactly the same as the case when a fun is received by a process after the purge.

The new strategy can optionally be enabled when building OTP during OTP 19, and will automatically be enabled if the runtime system is built with support for dirty schedulers.

For more information see the documentation of erlang:check_process_code/3.

Own Id: OTP-13833

Fixed unnecessary overestimation of heap size need during garbage collection.

Own Id: OTP-13851

## Erts 8.0.5

### Fixed Bugs and Malfunctions

Fixed a VM crash that occurred in a garbage collection of a process when it had received binaries. This bug was introduced in ERTS version 8.0 (OTP 19.0).

Own Id: OTP-13890

## Erts 8.0.4

### Fixed Bugs and Malfunctions

Fixed a VM crash that occurred in garbage collection of a process when it had received maps over the distribution. This bug was introduced in ERTS version 8.0 (OTP 19.0).

Own Id: OTP-13889

## Erts 8.0.3

### Fixed Bugs and Malfunctions

Fixed a race that could cause a lost wakeup of a process that timed out in a receive ... after. This bug was introduced in ERTS version 7.0.

Own Id: OTP-13798 Aux Id: OTP-11997

Fixed segfault after writing an erl crash dump.

Own Id: OTP-13799

## Erts 8.0.2

### Fixed Bugs and Malfunctions

Fix scheduler deadlock bug in ets:update_counter/4 when key is not found and inserting the default object causes the table to grow.

Own Id: OTP-13731 Aux Id: ERL-188

Fix VM abort "Overrun stack and heap" in garbage collection triggered by a bsl operation and some very specific heap conditions.

Own Id: OTP-13732 Aux Id: seq13142

## Erts 8.0.1

### Fixed Bugs and Malfunctions

A memory allocation bug in group_leader/2 could cause an emulator crash when garbage collecting a process that had been assigned a remote group leader. This bug was introduced in ERTS version 8.0.

Own Id: OTP-13716

## Erts 8.0

### Fixed Bugs and Malfunctions

The handling of on_load functions has been improved. The major improvement is that if a code upgrade fails because the on_load function fails, the previous version of the module will now be retained.

Own Id: OTP-12593

is_builtin(erlang, apply, 3) will now return true.

Own Id: OTP-13034

Fix enif_get_list_length to return false if list is improper or have length larger than UINT_MAX (did return true and an incorrect length value).

Own Id: OTP-13288 Aux Id: PR913

Cleanup hipe signal handling code for x86 and make it more portable.

Own Id: OTP-13341 Aux Id: PR951

Make file:datasync use fsync instead of fdatasync on Mac OSX.

Own Id: OTP-13411

Make sure to create a crash dump when running out of memory. This was accidentally removed in the erts-7.3 release.

Own Id: OTP-13419

A bug has been fixed where if erlang was started +B on a unix platform it would be killed by a SIGUSR2 signal when creating a crash dump.

Own Id: OTP-13425

Fix race between process_flag(trap_exit,true) and a received exit signal.

A process could terminate due to exit signal even though process_flag(trap_exit,true) had returned. A very specific timing between call to process_flag/2 and exit signal from another scheduler was required for this to happen.

Own Id: OTP-13452

Don't search for non-existing Map keys twice

For maps:get/2,3 and maps:find/2, searching for an immediate key, e.g. an atom, in a small map, the search was performed twice if the key did not exist.

Own Id: OTP-13459

When an abnormally large distribution message is about to be sent, the VM has been changed to create a crash dump instead of a core dump.

Own Id: OTP-13474

Fix erlang:process_info/2 type specification

Own Id: OTP-13485 Aux Id: ERL-123

Fix bug in open_port/2 with option {args, List}. A vm crash could be caused by an improper List.

Own Id: OTP-13489 Aux Id: ERL-127

Fixed a race-condition bug where the emulator could crash when erlang:system_profile/1,2 was enabled and a process had to be re-scheduled during termination.

Own Id: OTP-13494 Aux Id: ERL-126

Fixed bugs where the reduction counter was not handled correct.

Own Id: OTP-13512

Fixed typo in description of the EPMD_DUMP_REQ response.

Own Id: OTP-13517

Fixed a bug where a process flagged as sensitive would sometimes record its save_calls when it shouldn't.

Own Id: OTP-13540

Update configure scripts to not use hard-coded path for /bin/pwd and /bin/rm.

Own Id: OTP-13562

When passing a larger binary than the outputv callback of a linked-in driver can handle in one io vector slot, the binary is now split into multiple slots in the io vector. This change only effects system where the max size of an io vector slot is smaller then the word size of the system (e.g. Windows).

This change means that it is now possible on Windows to send binaries that are larger than 4GB to port_command, which is what is used for file:write, gen_tcp:send etc.

Own Id: OTP-13628

Workaround of Maps output in crashdumps. Currently the atom 'undefined' is generated instead of Map data if a Map type is encountered during crash.

Own Id: OTP-13657

### Improvements and New Features

The tracing support has been extended to allow a tracer module to be the trace event handler instead of a process or port. The tracer module makes it possible for trace tools to filter or manipulate trace event data without the trace event first having to be copied from the traced process or port.

With the introduction of this feature, erlang:trace(all|existing, _, _) now also returns the tracer process as part of the number of processes on which tracing is enabled. The is incompatible with the previous releases.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10267

Introduce LTTng tracing of Erlang Runtime System

For LTTng to be enabled OTP needs to be built with configure option --with-dynamic-trace=lttng.

This feature introduces tracepoints for schedulers, drivers, memory carriers, memory and async thread pool.

For a list of all tracepoints, see Runtime Tools User's Guide .

Own Id: OTP-10282

Make it possible to monitor/demonitor ports using the erlang:monitor/2 API. The process and port information functions have also been updated to include information about monitors from processes to ports.

Own Id: OTP-11384

Add microstate accounting

Microstate accounting is a way to track which state the different threads within ERTS are in. The main usage area is to pin point performance bottlenecks by checking which states the threads are in and then from there figuring out why and where to optimize.

Since checking whether microstate accounting is on or off is relatively expensive only a few of the states are enabled by default and more states can be enabled through configure.

There is a convenience module called msacc that has been added to runtime_tools that can assist in gathering and interpreting the data from Microstate accounting.

For more information see erlang:statistics(microstate_accounting, _) and the msacc module in runtime_tools.

Own Id: OTP-12345

The port of Erlang/OTP to the real-time operating system OSE has been removed.

Own Id: OTP-12573

Sharing preserved copy for messages and exit signals

Enable sharing preserved copy with configure option --enable-sharing-preserving. This will preserve sharing, within the process, when communication with other processes in the Erlang node. There is a trade-off, the copy is more costly but this cost can be reclaimed if there is a lot of sharing in the message. In addition literals will not be copied in a send except during a purge phase of the module where the literals are located. This feature is considered experimental in 19.0.

Own Id: OTP-12590 Aux Id: OTP-10251

Halfword BEAM has been removed.

Own Id: OTP-12883

Added os:perf_counter/1.

The perf_counter is a very very cheap and high resolution timer that can be used to timestamp system events. It does not have monoticity guarantees, but should on most OS's expose a monotonous time.

Own Id: OTP-12908

Support for a fragmented young heap generation. That is, the young heap generation can consist of multiple non continuous memory areas. The main reason for this change is to avoid extra copying of messages that could not be allocated directly on the receivers heap.

Own Id: OTP-13047

Erlang linked-in driver can now force the call to open_port to block until a call to erl_drv_init_ack is made inside the driver. This is useful when you want to do some asynchronous initialization, for example getting configuration from a pipe, and you want the initial open_port call to fail if the configuration is incomplete or wrong. See the erl_driver documentation for more details on the API.

Own Id: OTP-13086

Erlang linked-in drivers can now set their own pids as seen in erlang:port_info/1 by using the erl_drv_set_pid function. For more details see the erl_driver documentation.

Own Id: OTP-13087

The functionality behind erlang:open_port/2 when called with spawn or spawn_executable has been redone so that the forking of the new program is done in a separate process called erl_child_setup. This allows for a much more robust implementation that uses less memory and does not block the entire emulator if the program to be started is on an un-accessible NFS. Benchmarks have shown this approach to be about 3-5 times as fast as the old approach where the fork/vfork was done by erts. This is a pure stability and performance fix, however some error messages may have changed, which is why it is marked as a backwards incompatible change.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13088

Improved yielding strategy in the implementation of the following native functions:

erlang:binary_to_list/1 erlang:binary_to_list/3 erlang:bitstring_to_list/1 erlang:list_to_binary/1 erlang:iolist_to_binary/1 erlang:list_to_bitstring/1 binary:list_to_bin/1

This in order to improve performance of these functions.

Own Id: OTP-13096

All garbage collections of processes now bump reductions. Also the amount of reductions bumped when garbage collecting has been adjusted. It now better corresponds to the amount of work performed. This in order to improve the real time characteristics of the system.

Own Id: OTP-13097

New functions that can load multiple modules at once have been added to the 'code' module. The functions are code:atomic_load/1, code:prepare_loading/1, code:finish_loading/1, and code:ensure_modules_loaded/1.

Own Id: OTP-13111

The -boot_var option for erl now only supports a single key and single value (as documented). The option used to allow multiple key/value pairs, but that behavior was undocumented.

The function erl_prim_loader:start/3 has been removed. Its documentation has also been removed.

The undocumented and unsupported function erl_prim_loader:get_files/2 has been removed.

Own Id: OTP-13112

Low level BIF erlang:purge_module/1 is made more robust against incorrect use. Lingering processes that still refer the old code are now killed before the module is purged to prevent fatal VM behavior.

Own Id: OTP-13122

Improved dirty scheduler implementation. For more information see the NIF documentation.

The dirty scheduler support is still experimental.

The support for determining whether dirty NIF support exist or not at compile time using the C preprocessor macro ERL_NIF_DIRTY_SCHEDULER_SUPPORT has been removed.

The enif_is_on_dirty_scheduler() function has been removed. Use enif_thread_type() instead.

Own Id: OTP-13123

Various optimizations done to process dictionary access.

Own Id: OTP-13167

Added max_heap_size process flag. max_heap_size allows the user to limit the maximum heap used by a process. See erlang:process_flag for more details.

Own Id: OTP-13174

Allow dynamic drivers and NIF libraries to be built with gcc option -fvisibility=hidden for faster loading and more optimized code.

Own Id: OTP-13227

Add erlang:process_info(Pid, garbage_collection_info) which returns extended garbage_collection information. For more details see the documentation.

Own Id: OTP-13265

The functions erlang:list_to_integer/1 and string:to_integer/1 have been optimized for large inputs.

Own Id: OTP-13293

Improved memory allocation strategy for hipe native code on x86_64 (amd64) architectures by reserving enough low virtual address space needed for the HiPE/AMD64 small code model. The default virtual address area for hipe code is set to 512Mb, but can be changed with emulator flag +MXscs.

Own Id: OTP-13359

Introduction of configurable management of data referred to by the message queue of a process. Each process can be configured individually.

It is now possible to configure the message queue of a process, so that all data referred by it will be kept outside of the heap, and by this prevent this data from being part of garbage collections.

For more information see the documentation of process_flag(message_queue_data, MQD).

Own Id: OTP-13366 Aux Id: OTP-13047

Processes now yield when scanning large message queues and not finding a matching message. This in order to improve real time characteristics.

Own Id: OTP-13401

Optimized an erts internal function that is used to traverse erlang terms. The internal function was mainly used by term_to_binary and comparison of terms. Benchmarks have shown up to a 10% performance increase in those functions after the optimization.

Own Id: OTP-13440

Add the following NIF API functions:

enif_cpu_time enif_now_time enif_make_unique_integer enif_is_process_alive enif_is_port_alive enif_term_to_binary enif_binary_to_term enif_port_command

For details of what each function does, see the erl_nif documentation.

Own Id: OTP-13442

Optimize '++' operator and lists:append/2 by using a single pass to build a new list while checking for properness.

Own Id: OTP-13487

Handle terms (pids,ports and refs) from nodes with a 'creation' value larger than 3. This is a preparation of the distribution protocol to allow OTP 19 nodes to correctly communicate with future nodes (20 or higher). The 'creation' value differentiates different incarnations of the same node (name).

Own Id: OTP-13488

Don't send unasked for systemd notifications in epmd

Own Id: OTP-13493 Aux Id: PR-999

The enif_send API has been extended to allow NULL to be used as the message environment. When used this way, a message environment is implicitly created and the given term is copied into that environment before sending. This can be an optimization if many small messages are being sent by the nif.

Own Id: OTP-13495

The tracing support has been extended to allow tracing on ports. Ports can be traced on using the 'ports', 'send' and 'receive' trace flags.

The first argument of erlang:trace/3 has been extended so that 'all', 'existing' and 'new' now include both processes and ports. New Tracee variants, 'all_processes', 'all_ports', 'existing_processes' etc have been added to specify only processes or ports.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13496

When the 'procs' trace flag is enabled, a 'spawned' trace event is now also generated by a newly created process. The previous event 'spawn' remains, but as it is generated by the process that did the spawn, it is not guaranteed that it is ordered with other trace events from the newly spawned process. So when tracking the lifetime of a process this new event should be used as the creation event.

This new trace event is marked as an incompatibility because tools that expect certain trace events when enabling 'procs' will have to updated.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13497

Add the erlang:match_spec_test/3 function. The functions allows the testing of match specifications for both tracing and ets tables. It can be used to test that a match specification does the expected filtering on specific data. It also returns more verbose error reasons for incorrectly constructed match specifications.

Own Id: OTP-13501

The erts internal tracing support has been changed to have much less overhead and be more scalable.

This rewrite does not break any backwards incompatibilities, but it does change the ordering of some trace messages when compared to previous releases. It should be noted that this only applies to trace messages sent to processes or ports, it does not apply to the new tracer module. However in future releases they may also be effected by this.

Trace messages are only guaranteed to be ordered from one traced process or port. In previous releases this was not visible as a 'send' trace message would always arrive before the corresponding 'receive' trace message that is no longer always the case. This also means that timestamped trace messages may seem to arrive out of order as the timestamp is taken when the event is triggered and not when it is put in the queue of the tracer.

Own Id: OTP-13503

Add possibility to filter send and receive trace with match specifications.

Own Id: OTP-13507

Add maps:update_with/3,4 and maps:take/2

Own Id: OTP-13522 Aux Id: PR-1025

Introduce LTTng tracing via Erlang tracing.

For LTTng to be enabled OTP needs to be built with configure option --with-dynamic-trace=lttng.

The dynamic trace module dyntrace is now capable to be used as a LTTng sink for Erlang tracing. For a list of all tracepoints, see Runtime Tools User's Guide .

This feature also introduces an incompatible change in trace tags. The trace tags gc_start and gc_end has been split into gc_minor_start, gc_minor_end and gc_major_start, gc_major_end.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13532

Print heap pointers for garbing processes during crashdump

Own Id: OTP-13541 Aux Id: PR-1026

Changed and improved low level memory statistics returned by erlang:system_info/1. The info for erts_mmap has been moved from mseg_alloc to its own section returned by {allocator, erts_mmap}.

Own Id: OTP-13560

Add enif_snprintf to the NIF API

The function enif_snprintf is similar to snprintf call but can handle formatting of Erlang terms via %T format specifier.

Own Id: OTP-13580

The warning in the documentation for erlang:raise/3 has been removed. It is now officially perfectly fine to use raise/3 in production code.

Own Id: OTP-13599

Fix bugs caused by the VM sometimes truncating object sizes or offsets to 32 bits on 64-bit hosts. These bugs were mainly found when working with large unicode strings and nifs environments.

Own Id: OTP-13606

Add -start_epmd command line option, this lets you disable automatic starting of epmd when starting a distributed node.

Add -epmd_module command line option, this lets you specify a module to register and look-up node names in. The default module is erl_epmd.

Own Id: OTP-13627

erlang:halt now truncates strings longer than 200 characters instead of failing with badarg.

Own Id: OTP-13630

Fix possible race in poller wake up on windows

Own Id: OTP-13634

## Erts 7.3.1.6

### Improvements and New Features

List subtraction (The -- operator) will now yield properly on large inputs.

Own Id: OTP-15371

## Erts 7.3.1.5

### Fixed Bugs and Malfunctions

Fixed small memory leak that could occur when sending to a terminating port.

Own Id: OTP-14609 Aux Id: ERIERL-238

## Erts 7.3.1.4

### Fixed Bugs and Malfunctions

Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02.

Own Id: OTP-14491

Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-14514

A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.

This bug was introduced in ERTS version 7.0 (OTP 18.0).

Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468

Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).

Own Id: OTP-14590 Aux Id: ERL-474

## Erts 7.3.1.3

### Fixed Bugs and Malfunctions

A bug has been fixed where if erlang was started +B on a unix platform it would be killed by a SIGUSR2 signal when creating a crash dump.

Own Id: OTP-13425 Aux Id: ERL-94

Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.

Own Id: OTP-13866

Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:

erl_drv_send_term() driver_send_term() erl_drv_output_term() driver_output_term() enif_send() enif_port_command()

Own Id: OTP-13869

Fix bug in binary_to_term for binaries created by term_to_binary with option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.

Own Id: OTP-14159 Aux Id: ERL-340

## Erts 7.3.1.2

### Fixed Bugs and Malfunctions

Fixed a race that could cause a lost wakeup of a process that timed out in a receive ... after. This bug was introduced in ERTS version 7.0.

Own Id: OTP-13798 Aux Id: OTP-11997

Fixed segfault after writing an erl crash dump.

Own Id: OTP-13799

## Erts 7.3.1.1

### Fixed Bugs and Malfunctions

Fix scheduler deadlock bug in ets:update_counter/4 when key is not found and inserting the default object causes the table to grow.

Own Id: OTP-13731 Aux Id: ERL-188

## Erts 7.3.1

### Fixed Bugs and Malfunctions

process_info(Pid, last_calls) did not work for Pid /= self().

Own Id: OTP-13418

Make sure to create a crash dump when running out of memory. This was accidentally removed in the erts-7.3 release.

Own Id: OTP-13419

Schedulers could be woken by a premature timeout on Linux. This premature wakeup was however harmless.

Own Id: OTP-13420

A process communicating with a port via one of the erlang:port_* BIFs could potentially end up in an inconsistent state if the port terminated during the communication. When this occurred the process could later block in a receive even though it had messages matching in its message queue.

This bug was introduced in erts version 5.10 (OTP R16A).

Own Id: OTP-13424 Aux Id: OTP-10336

The reference count of a process structure could under rare circumstances be erroneously managed. When this happened invalid memory accesses occurred.

Own Id: OTP-13446

Fix race between process_flag(trap_exit,true) and a received exit signal.

A process could terminate due to exit signal even though process_flag(trap_exit,true) had returned. A very specific timing between call to process_flag/2 and exit signal from another scheduler was required for this to happen.

Own Id: OTP-13452

## Erts 7.3

### Fixed Bugs and Malfunctions

The '-path' flag to 'erl' has been documented. This flag replaces the path specified in the boot script. It has always existed, but was earlier only documented in SASL (script).

Own Id: OTP-13060

The call_time tracing functionality internally used a time based on OS system time in order to measure call time which could cause erroneous results if OS system time was changed during tracing.

This functionality now use Erlang monotonic time in order to measure time. Besides fixing the erroneous results due to OS system time being used, the results are often also better since Erlang monotonic time often has better accuracy and precision.

Own Id: OTP-13216

Fix behaviour of -delay_write command line switch of epmd, which is used for debugging - in some cases epmd was sleeping twice the requested amount of time.

Own Id: OTP-13220

Fix race between timeout and exit signal that could cause a process to ignore the exit signal and continue execution. Bug exist since OTP 18.0.

Own Id: OTP-13245

Fix bug in erlang:halt/1,2 for large exit status values, causing either badarg (on 32-bit) or exit with a crash dump and/or core dump (on 64-bit). Make erlang:halt/1,2 tolerate any non negative integer as exit status and truncate high order bits if the OS does not support it.

Own Id: OTP-13251 Aux Id: ERL-49

gen_tcp:accept/2 was not time warp safe. This since it used the same time as returned by erlang:now/0 when calculating timeout. This has now been fixed.

Own Id: OTP-13254 Aux Id: OTP-11997, OTP-13222

Fix faulty error handling when writing to a compressed file.

Own Id: OTP-13270

Fix sendfile usage for large files on FreeBSD

Own Id: OTP-13271

Fix bug that could cause process_info(P,current_location) to crash emulator for hipe compiled modules.

Own Id: OTP-13282 Aux Id: ERL-79

Out of memory errors have been changed to cause an exit instead of abort.

Own Id: OTP-13292

When calling garbage_collect/[1,2] or check_process_code/[2,3] from a process with a higher priority than the priority of the process operated on, the run queues could end up in an inconsistent state. This bug has now been fixed.

Own Id: OTP-13298 Aux Id: OTP-11388

A workaround for an issue with older gcc versions (less than 5) and inline assembly on 32-bit x86 caused an emulator crash when it had been compiled with a newer gcc version. An improved configure test, run when building OTP, now detects whether the workaround should be used or not.

Own Id: OTP-13326 Aux Id: ERL-80

### Improvements and New Features

Introduced new statistics functionality in order to more efficiently retrieve information about run able and active processes and ports. For more information see:

statistics(total_run_queue_lengths) statistics(run_queue_lengths) statistics(total_active_tasks) statistics(active_tasks)

Own Id: OTP-13201

Time warp safety improvements.

Introduced the options monotonic_timestamp, and strict_monotonic_timestamp to the trace, sequential trace, and system profile functionality. This since the already existing timestamp option is not time warp safe.

Introduced the option safe_fixed_monotonic_time to ets:info/2 and dets:info/2. This since the already existing safe_fixed option is not time warp safe.

Own Id: OTP-13222 Aux Id: OTP-11997

Fix a register race where down nodes goes undetected in epmd

Own Id: OTP-13301

Improved the gcc inline assembly implementing double word atomic compare and exchange on x86/x86_64 so that it also can be used when compiling with clang.

Own Id: OTP-13336

An optimization preventing a long wait for a scheduler thread looking up information about a process executing on another scheduler thread had unintentionally been lost in erts-5.10 (OTP R16A). This optimization has now been reintroduced.

Own Id: OTP-13365 Aux Id: OTP-9892

## Erts 7.2.1.1

### Improvements and New Features

Introduced new statistics functionality in order to more efficiently retrieve information about run able and active processes and ports. For more information see:

statistics(total_run_queue_lengths) statistics(run_queue_lengths) statistics(total_active_tasks) statistics(active_tasks)

Own Id: OTP-13201

## Erts 7.2.1

### Fixed Bugs and Malfunctions

Revert "Fix erroneous splitting of emulator path"

Own Id: OTP-13202

Fix HiPE enabled emulator for FreeBSD.

Own Id: OTP-13204 Aux Id: pr926

## Erts 7.2

### Fixed Bugs and Malfunctions

Small documentation fixes

Own Id: OTP-13017

Fix memory corruption bug caused by disabling distribution and then re-enable distribution with a node name that has previously been used by a remote node.

Own Id: OTP-13076 Aux Id: seq12959

Renamed variables with name bool as Visual Studio 2015 now treats this is a keyword.

Own Id: OTP-13079

erl_prim_loader has not supported custom loaders for several releases. In the documentation for erl_prim_loader, all references to custom loaders have now been removed.

Own Id: OTP-13102

Fixed compilation of erts together with libc versions that do not define __uint32_t.

Own Id: OTP-13105

erl -make now returns non-zero exit codes on failure

Own Id: OTP-13107

Fix crash on init:restart in embedded mode caused by on_load handler process not being relaunched leading to load failure for modules such as crypto and asn1rt_nif that need it to be present for correct NIF loading.

Own Id: OTP-13115

Fix maps decode in erlang:binary_to_term/1

Decoding a term with a large (HAMT) map in an small (FLAT) map could cause a critical error if the external format was not produced by beam.

Own Id: OTP-13125

Fix very rare bug in GC when big maps with a lot of hash collisions from a remote node are waiting in inner message queue.

Own Id: OTP-13146

Fixed a bug that could cause a crash dump to become almost empty.

Own Id: OTP-13150

### Improvements and New Features

Updated the xmllint target to just check the xml files with real documentation content.
Corrected some errors and added some missing target in the DTD's.

Own Id: OTP-13026

Add function enif_getenv to read OS environment variables in a portable way from NIFs.

Own Id: OTP-13147

## Erts 7.1

### Fixed Bugs and Malfunctions

Fix bug in ETS that could cause stray objects marked for deletion to occasionally be missed by the cleanup done by safe_fixtable(_,false).

Own Id: OTP-12870

Fixed VM crash that could occur if a trace port was linked to a process, and the trace port terminated abnormally while handling a trace message. This bug has always existed in the runtime system with SMP support.

Own Id: OTP-12901

Instead of aborting, the vm now creates a crash dump when a system process is terminated.

Own Id: OTP-12934

Fixed a rare emulator dead lock that occurred when erlang:process_flag(priority,...) was called by a process that was also scheduled for an internal system activity.

Own Id: OTP-12943

The runtime system on various posix platforms (except for Linux and Solaris) could crash when large amounts of file-descriptors were in use.

Own Id: OTP-12954

A beam file compiled by hipe for an incompatible runtime system was sometimes not rejected by the loader, which could lead to vm crash. This fix will also allow the same hipe compiler to be used by both normal and debug-built vm.

Own Id: OTP-12962

Fix bug in maps:merge/2 when called by hipe compiled code that could cause vm crash. Bug exists since erts-7.0 (OTP 18.0).

Own Id: OTP-12965

When tracing with process_dump option, the VM could abort if there was an ongoing binary match somewhere in the call stack of the traced process.

Own Id: OTP-12968

Fixed possible output deadlock in tty driver when hitting "CTRL-C" in a non-smp emulator shell on unix.

Own Id: OTP-12987 Aux Id: Seq12947

Fix binary_to_integer to throw badarg for "+" and "-" similar to list_to_integer.

Own Id: OTP-12988

Suppress warning of unused argument when using macro enif_make_pid.

Own Id: OTP-12989

### Improvements and New Features

Changed default clock source used for OS system time on MacOS X to gettimeofday() in order to improve performance. The system can be configured during build to use the previously used higher resolution clock source by passing the switch --with-clock-resolution=high when configuring the build.

Own Id: OTP-12945 Aux Id: OTP-12892

Added the configure option --disable-saved-compile-time which disables saving of compile date and time in the emulator binary.

Own Id: OTP-12971

## Erts 7.0.3

### Fixed Bugs and Malfunctions

Fixed a binary memory leak when printing to shell using the tty driver (i.e. not -oldshell).

Own Id: OTP-12941

Fix a bug where the standard error port sometimes crashes with eagain as the reason.

Own Id: OTP-12942

When tracing with process_dump option, the VM could abort if there was an ongoing binary match somewhere in the call stack of the traced process./

Own Id: OTP-12968

## Erts 7.0.2

### Fixed Bugs and Malfunctions

A process could end up in an inconsistent half exited state in the runtime system without SMP support. This could occur if the processes was traced by a port that it also was linked to, and the port terminated abnormally while handling a trace message for the process.

This bug has always existed in the runtime system without SMP support, but never in the runtime system with SMP support.

Own Id: OTP-12889 Aux Id: seq12885

Removed unnecessary copying of data when retrieving corrected Erlang monotonic time.

Own Id: OTP-12894

Changed default OS monotonic clock source chosen at build time. This in order to improve performance. The behavior will now on most systems be that (both OS and Erlang) monotonic time stops when the system is suspended.

If you prefer that monotonic time elapse during suspend of the machine, you can pass the command line argument --enable-prefer-elapsed-monotonic-time-during-suspend to configure when building Erlang/OTP. The configuration stage will try to find such a clock source, but might not be able to find it. Note that there might be a performance penalty associated with such a clock source.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12895

erlang:system_info(end_time) returned a faulty value on 32-bit architectures.

Own Id: OTP-12896

### Improvements and New Features

The configure command line argument --enable-gettimeofday-as-os-system-time has been added which force usage of gettimeofday() for OS system time. This will improve performance of os:system_time() and os:timestamp() on MacOS X, at the expense of worse accuracy, resolution and precision of Erlang monotonic time, Erlang system time, and OS system time.

Own Id: OTP-12892

## Erts 7.0.1

### Fixed Bugs and Malfunctions

Fix a rare hanging of the VM seen to happen just after emulator start. Bug exists since R14.

Own Id: OTP-12859 Aux Id: seq12882

## Erts 7.0

### Fixed Bugs and Malfunctions

Fix issuing with spaces and quoting in the arguments when using erlang:open_port spawn_executable on windows. The behavior now mimics how unix works. This change implies a backwards incompatibility for how spawn_executable works on windows.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11905

Fix global call trace when hipe compiled code call beam compiled functions. Tracing of beam functions should now alway work regardless who the caller is.

Own Id: OTP-11939

Correct cache alignment for ETS write_concurrency locks to improve performance by reduced false sharing. May increase memory footprint for tables with write_concurrency.

Own Id: OTP-11974

All possibly blocking operations in the fd/spawn and terminal driver have been converted to non-blocking operations. Before this fix it was possible for the VM to be blocked for a long time if the entity consuming stdout/stderr did not consume it fast enough.

Own Id: OTP-12239

Add missing overhead for offheap binaries created from external format. This fix can improve the garbage collection of large binaries originating from binary_to_term or messages from remote nodes.

Own Id: OTP-12554

Ensure hashing of zero is consistent

Erlang treats positive and negative zero as equal:

true = 0.0 =:= 0.0/-1

However, Erlangs hash functions: hash, phash and phash2 did not reflect this behaviour. The hash values produced by the different hash functions would not be identical for positive and negative zero.

This change ensures that hash value of positive zero is always produced regardless of the signedness of the zero float, i.e.,

true = erlang:phash2(0.0) =:= erlang:phash2(0.0/-1)

Own Id: OTP-12641

Ensure NIF term creation disallows illegal floating point values and too long atoms. Such values will cause a NIF to throw badarg exception when it returns.

Own Id: OTP-12655

Fixed building of Map results from match_specs

A faulty "box-value" entered into the heap which could cause a segmentation fault in the garbage collector if it was written on a heap fragment.

Own Id: OTP-12656

Fix hipe bug when matching a "writable" binary. The bug has been seen to sometimes cause a failed binary matching of a correct utf8 character, but other symptoms are also possible.

Own Id: OTP-12667

Keep dirty schedulers from waking other schedulers.

Own Id: OTP-12685

Disable floating point exceptions if the VM is compiled by clang/llvm. This is a known long-standing problem in clang/llvm.

Own Id: OTP-12717

Fix bug in file:sendfile for FreeBSD causing not the entire file to be sent.

Own Id: OTP-12720

Fix the broken Android support in erl_child_setup.c

Own Id: OTP-12751

Faulty statistics reported by the fix_alloc allocator.

Own Id: OTP-12766

Fix two erts_snprintf() calls to correct sizes.

- run_erl.c (ose): Use the size of the signal type, not its pointer. - erl_node_tables.c: Use the size of the _BUFFER in erts_snprintf() to make sure we can use the full space.

Own Id: OTP-12771

Delayed memory allocations could be delayed an unnecessarily long time.

Own Id: OTP-12812

Make sure that timeouts on a pool of acceptors are released in the correct order.

Own Id: OTP-12817

Fix segmentation fault in module_info for deleted modules

Own Id: OTP-12820

Fix garbage collection of literals in code purge

During code purging and check_process_code, the checking of the binary reference embedded in the match binary state was omitted for the tracing tests. This would cause the binary match state to reference deallocated memory.

Own Id: OTP-12821

A bug has been corrected for gen_tcp:close so when {linger,{true,0}} is in effect it does not wait for data in the driver queue to transfer out before closing the port. Bug fix by Rory Byrne.

Own Id: OTP-12840

The documentation of the driver callback start() erroneously stated that a return value of ERL_DRV_ERROR_ERRNO caused the error value to be passed via erl_errno when it should have been errno.

Own Id: OTP-12855

### Improvements and New Features

Add md5 and module entries to ?MODULE:module_info/0/1 and remove obsolete entry 'import'.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11940

Debug function erlang:display/1 shows content of binaries and bitstrings, not only the length.

Own Id: OTP-11941

The time functionality of Erlang has been extended. This both includes a new API for time, as well as time warp modes which alters the behavior of the system when system time changes. You are strongly encouraged to use the new API instead of the old API based on erlang:now/0. erlang:now/0 has been deprecated since it is and forever will be a scalability bottleneck. For more information see the Time and Time Correction chapter of the ERTS User's Guide.

Besides the API changes and time warp modes a lot of scalability and performance improvements regarding time management has been made internally in the runtime system. Examples of such improvements are scheduler specific timer wheels, scheduler specific BIF timer management, parallel retrieval of monotonic time and system time on systems with primitives that are not buggy.

Own Id: OTP-11997

erlang:function_exported(M, F, A) will now return true if M:F/A refers to a BIF.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12099

New BIF: erlang:get_keys/0, lists all keys associated with the process dictionary. Note: erlang:get_keys/0 is auto-imported.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12151 Aux Id: seq12521

Make distributed send of large messages yield to improve real-time characteristics.

Own Id: OTP-12232

Use high accuracy poll timeouts

Where available, use poll/select API's that can handle time resolutions less than 1ms. In the cases where such API's are not available the timeout is rounded up to the nearest ms.

Own Id: OTP-12236

The internal group to user_drv protocol has been changed to be synchronous in order to guarantee that output sent to a process implementing the user_drv protocol is printed before replying. This protocol is used by the standard_output device and the ssh application when acting as a client.

This change changes the previous unlimited buffer when printing to standard_io and other devices that end up in user_drv to 1KB.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12240

The previously introduced "eager check I/O" feature is now enabled by default.

Eager check I/O can be disabled using the erl command line argument: +secio false

Characteristics impact compared to previous default:

Lower latency and smoother management of externally triggered I/O operations. A slightly reduced priority of externally triggered I/O operations.

Own Id: OTP-12254 Aux Id: OTP-12117

Properly support maps in match_specs

Own Id: OTP-12270

The notice that a crashdump has been written has been moved to be printed before the crashdump is generated instead of afterwords. The wording of the notice has also been changed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12292

New function ets:take/2. Works the same as ets:delete/2 but also returns the deleted object(s).

Own Id: OTP-12309

Tracing with cpu_timestamp option has been enabled on Linux.

Own Id: OTP-12366

ets:info/1,2 now contains information about whether write_concurrency or read_concurrency is enabled.

Own Id: OTP-12376

Improved usage of gcc's builtins for atomic memory access. These are used when no other implementation of atomic memory operations is available. For example, when compiling for ARM when libatomic_ops is not available.

The largest improvement will be seen when compiling with a gcc with support for the __atomic_* builtins (using a gcc of at least version 4.7), but also when only the legacy __sync_* builtins are available (using a gcc of at least version 4.1) an improvement can be seen.

For more information see the "Atomic Memory Operations and the VM" section of $ERL_TOP/HOWTO/INSTALL.md.

Own Id: OTP-12383

Introduce math:log2/1 function to math module.

Own Id: OTP-12411

The documentation of the Abstract Format (in the ERTS User's Guide) has been updated with types and specification. (Thanks to Anthony Ramine.)

The explicit representation of parentheses used in types of the abstract format has been removed. Instead the new functions erl_parse:type_inop_prec() and erl_parse:type_preop_prec() can be used for inserting parentheses where needed.

Own Id: OTP-12492

Remove perfctr support

Development of perfctr in the linux kernel ceased in 2010. The perfctr support code in the Erlang VM is thus effectively dead code and therefor removed.

Own Id: OTP-12508

zlib:inflateChunk/2 has been added. It works like zlib:inflate/2, but decompresses no more data than will fit in the buffer configured by zlib:setBufSize/2.

Own Id: OTP-12548

Use linear search for small select_val arrays

Own Id: OTP-12555

New BIF ets:update_counter/4 with a default object as argument, which will be inserted in the table if the key was not found.

Own Id: OTP-12563

Export missing types from zlib module

Own Id: OTP-12584

Use persistent hashmaps for large Maps

Maps will use a persistent hashmap implementation when the number of pairs in a Map becomes sufficiently large. The change will occur when a Map reaches 33 pairs in size but this limit might change in the future.

The most significant impact for the user by this change is speed, and to a lesser degree memory consumption and introspection of Maps. Memory consumption size is probalistic but lesser than gb_trees or dict for instance. Any other impacts will be transparent for the user except for the following changes.

Semantics of Maps have changed in two incompatible ways compared to the experimental implementation in OTP 17:

Hashing of maps is done different by erlang:phash2/1,2, erlang:phash/1 and erlang:hash/2. Comparing two maps with ==, /=, =<, <, >= and >, is done different if the keys contain floating point numbers.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12585

Scalability improvement for erlang:make_ref/0, and other functionality that create references. Each scheduler now manage its own set of references. By this no communication at all is needed when creating references.

Previous implementation generated a strictly monotonically increasing sequence of references corresponding to creation time on the runtime system instance. This is not the case with current implementation. You can only expect reference to be unique. The Erlang/OTP documentation has never mentioned anything else but the uniqueness property, so this change is fully compatible. The only reason we've marked this as a potential incompatibility is since an early draft for an Erlang specification mentions strict monotonicity as a property.

If you need to create data with a strict monotonicity property use erlang:unique_integer([monotonic]). Do not use the deprecated erlang:now().

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12610

Enable different abort signal from heart

By using environment variable HEART_KILL_SIGNAL, heart can now use a different signal to kill the old running Erlang.

By default the signal is SIGKILL but SIGABRT may also be used by setting environment variable: HEART_KILL_SIGNAL=SIGABRT

Own Id: OTP-12613 Aux Id: seq12826

Update autconf to latest version 2015-03-04

Own Id: OTP-12646

Optimization of timers internally in the VM. This include process timers (receive ... after), port timers (driver_set_timer()) as well as BIF timers (erlang:send_after()/erlang:start_timer()).

Each scheduler thread now has its own lock-free timer service instead of one locked central service. This dramatically improves performance of timer management on systems with a large amount of schedulers and timers.

The timer service internal data structure has also been optimized to be able to handle more timers than before. That is, each timer service is by its self able to handle more timers without dramatic performance loss than the old centralized timer service.

The API of BIF timers has also been extended. Timeout values are for example no longer limited to 32-bit integers. For more information see the documentation of erlang:start_timer/4, erlang:send_after/4, erlang:cancel_timer/2, and erlang:read_timer/2.

Characteristics impact: Calls to the synchronous versions of erlang:cancel_timer(), and erlang:read_timer() may take substantially longer time to complete than before. This occur when the timer that is accessed is managed by a remote scheduler. You typically want to use the new asynchronous option in order to avoid blocking the calling process.

Own Id: OTP-12650 Aux Id: OTP-11997

Specialize instructions from common assembler patterns

Specialize common instructions of rem, band, minus and plus in the beam loader. This will reduce the number of fetches and thus lessen the instruction dispatch pressure during runtime and speed up those operations in some common cases.

Specialize move patterns from x-registers to the stack with a new move_window instruction. This change will reduce instruction dispatch pressure.

Own Id: OTP-12690

Fix cross compilation for Android.

Own Id: OTP-12693

Fix incorrect use of autoconf macro AC_EGREP_CPP, which could cause faulty configuration if run from a path containing the string 'yes'.

Own Id: OTP-12706

Minimal Java version is now 1.6

Own Id: OTP-12715

Send format and args on process exit to error_logger

Previously, the emulator would generate a whole string with values and call the error_logger passing "~s~n". This changes it to a format string containing ~p with the respective values as arguments.

Own Id: OTP-12735

Map error logger warnings to warning messages by default.

Own Id: OTP-12755

Configure architecture ppc64le architecture as a ppc64

Own Id: OTP-12761

Add function enif_raise_exception to allow a NIF to raise an error exception with any type of reason.

Own Id: OTP-12770

Optimized node table statistics retrieval.

Own Id: OTP-12777

Map beam error logger warnings to warning messages by default. Previously these messages were mapped to the error channel by default.

Own Id: OTP-12781

gen_tcp:shutdown/2 is now asynchronous

This solves the following problems with the old implementation:

It doesn't block when the TCP peer is idle or slow. This is the expected behaviour when shutdown() is called: the caller needs to be able to continue reading from the socket, not be prevented from doing so.

It doesn't truncate the output. The current version of gen_tcp:shutdown/2 will truncate any outbound data in the driver queue after about 10 seconds if the TCP peer is idle of slow. Worse yet, it doesn't even inform anyone that the data has been truncated: 'ok' is returned to the caller; and a FIN rather than an RST is sent to the TCP peer.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12797

Introduced delayed node table GC. This in order to avoid oscillation of entries in and out of the tables. The oscillation caused unnecessary lock contention on the table locks. The delay length can be set by passing the +zdntgc command line argument.

Characteristics impact: The tables can grow to very large sizes with unused entries if the node is get huge amounts of short lived connections from other nodes. This problem can be alleviated by shortening the length of the delay using the +zdntgc command line argument.

Own Id: OTP-12802

Improved implementation of erlang:statistics(io) in order to reduce contention between schedulers.

Characteristics impact: The actual call to erlang:statistics(io) takes longer time to complete, but the overall impact on the system is improved.

Own Id: OTP-12842

There are many cases where user code needs to be able to distinguish between a socket that was closed normally and one that was aborted. Setting the option {show_econnreset, true} enables the user to receive ECONNRESET errors on both active and passive sockets.

Own Id: OTP-12843

Do not preallocate too large event pool

A default pool size of 4000 is too excessive for the common case. This corresponds directly to the number of threads in the system. Change ERTS_TS_EV_ALLOC_DEFAULT_POOL_SIZE to 2048. Change ERTS_TS_EV_ALLOC_POOL_SIZE to 32.

Own Id: OTP-12849

## Erts 6.4.1.7

### Fixed Bugs and Malfunctions

A process communicating with a port via one of the erlang:port_* BIFs could potentially end up in an inconsistent state if the port terminated during the communication. When this occurred the process could later block in a receive even though it had messages matching in its message queue.

This bug was introduced in erts version 5.10 (OTP R16A).

Own Id: OTP-13424 Aux Id: OTP-10336

Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.

Own Id: OTP-13866

Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:

erl_drv_send_term() driver_send_term() erl_drv_output_term() driver_output_term() enif_send() enif_port_command()

Own Id: OTP-13869

Fix bug in binary_to_term for binaries created by term_to_binary with option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.

Own Id: OTP-14159 Aux Id: ERL-340

Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.

Own Id: OTP-14514

Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).

Own Id: OTP-14590 Aux Id: ERL-474

## Erts 6.4.1.6

### Fixed Bugs and Malfunctions

When calling garbage_collect/[1,2] or check_process_code/[2,3] from a process with a higher priority than the priority of the process operated on, the run queues could end up in an inconsistent state. This bug has now been fixed.

Own Id: OTP-13298 Aux Id: OTP-11388

## Erts 6.4.1.5

### Fixed Bugs and Malfunctions

Fixed a bug that could cause a crash dump to become almost empty.

Own Id: OTP-13150

## Erts 6.4.1.4

### Fixed Bugs and Malfunctions

The 'raw' socket option could not be used multiple times in one call to any e.g gen_tcp function because only one of the occurrences were used. This bug has been fixed, and also a small bug concerning propagating error codes from within inet:setopts/2.

Own Id: OTP-11482 Aux Id: seq12872

## Erts 6.4.1

### Fixed Bugs and Malfunctions

The VTS mode in Common Test has been modified to use a private version of the Webtool application (ct_webtool).

Own Id: OTP-12704 Aux Id: OTP-10922

## Erts 6.4

### Fixed Bugs and Malfunctions

Fix missing quotation in the LM_FIND_EMU_CC autoconf macro which could cause build failures.

Own Id: OTP-12388

Fix erroneous printout of monitors in crashdump file.

Own Id: OTP-12537

The runtime system without SMP support could crash in the BIF port_control/3 if the port that was being accessed died during the call to the BIF.

Own Id: OTP-12544 Aux Id: Seq12777

Avoid corrupt oversized integer to be created from binary matching. Instead throw system_limit exception which is the correct behavior. A peculiar symptom of this bug was that bitwise operations (band, bor, bxor) on such oversized integers could return the empty list []. Credit: Mikael Pettersson, Nico Kruber

Own Id: OTP-12556

A race condition when calling port_info/1 could cause a memory fault has been fixed.

Own Id: OTP-12587

Fix comparison of exact terms. An overflow that could cause faulty comparisons has been fixed. Comparison of exact terms is exclusively used within Maps.

Own Id: OTP-12623

Fix bug in list_to_integer/1 for very long lists that could cause VM crash.

Own Id: OTP-12624

### Improvements and New Features

Introduced a runtime system internal 64-bit API for atomic memory operations.

Own Id: OTP-12351

Add command line argument option for the initial size of process dictionaries.

Use '+hpds <size>' to set initial process dictionary size for spawned processes.

Own Id: OTP-12535 Aux Id: seq12809

Fix documentation on $char for Unicode

Own Id: OTP-12545

## Erts 6.3.1

### Fixed Bugs and Malfunctions

Fix getifaddrs realloc pointer error

When a buffer was exhausted and subsequently reallocated, we could get an unsafe pointer pointing to faulty memory.

For this to occur we would need to have a large number of interfaces and a reallocation of memory to a lower addresses.

The symptom would be garbage returned from erlang:port_control(Port, 25, []) (prim_inet:getifaddrs(Port) resulting in a badarg) or a segmentation fault.

Own Id: OTP-12445

Don't close all file descriptors twice in child_setup

The commit c2b4eab25c907f453a394d382c04cd04e6c06b49 introduced an error in which child_setup erroneously tried to close all file descriptors twice.

Use closefrom() if available when closing all file descriptors.

The function closefrom() was only used in the vfork() case before but is now also used in the fork() case if available.

Own Id: OTP-12446

During a crashdump all file descriptors are closed to ensure the closing of the epmd port and to reserve a file descriptor for the crashdump file.

If a driver (third party library) cannot handle closing of sockets this could result in a segmentation fault in which case a crashdump would not be produced. This is now fixed by only closing inets sockets via an emergency close callback to the driver and thus closing the epmd socket.

Own Id: OTP-12447

## Erts 6.3

### Fixed Bugs and Malfunctions

Fix HiPE debug lock checking on OS X 64bit

Position-independent code is mandatory on OS X. We use r11 as an intermediate register to fill BIF_P->hipe.bif_callee. This fixes the following error when doing `make debug FLAVOR=smp`:

clang -cc1as: fatal error: error in backend: 32-bit absolute addressing is not supported in 64-bit mode

Own Id: OTP-12188

Fix race bug that could cause VM crash in erlang:port_get_data/1 if the port was closed by a concurrent process. Also fix fatal bug if port_set_data/2 is called with a non-immediate data term. Both bugs exist since R16B01.

Own Id: OTP-12208

Correct make variable SSL_DED_LD_RUNTIME_LIBRARY_PATH when erl_xcomp_sysroot ends with a slash.

Own Id: OTP-12216 Aux Id: seq12700

Fix two cases of unreachable code caused by false use of assigment operators.

Own Id: OTP-12222

Fix bug when hipe compiled code makes tail call to a BIF that disables GC while trapping (sush as binary_to_list, list_to_binary, binary_to_term, term_to_binary).

Own Id: OTP-12231

Fix bug when a migrated empty memory carrier is reused just before it should be destroyed by the thread that created it.

Own Id: OTP-12249

Prevents compile-time errors in NIFs, when the compiler is instructed to treat missing field initializers as errors, by adding an initializer for the new options field which was added to ErlNifEntry for 17.3.

Own Id: OTP-12266

Fixed CPU topology detection on FreeBSD systems where Erlang/OTP is compiled by new C compilers (including, but possibly not limited to, gcc 4.9 and clang).

Own Id: OTP-12267

Use C99 function isfinite() instead of finite() when available on non GCC compilers.

Own Id: OTP-12268

Fix bug on windows where an incorrect number of links could be returned when doing file:read_file_info on a directory.

Own Id: OTP-12269

Fix rare bug when purging module on VM started with +Meamin.

Own Id: OTP-12273

Repair run_erl terminal window size adjustment sent from to_erl. This was broken in OTP 17.0 which could lead to strange cursor behaviour in the to_erl shell.

Own Id: OTP-12275 Aux Id: seq12739

Fixed bug on windows causing gen_tcp/udp to return an error when given an fd to work with.

Own Id: OTP-12289

Fix various internal erts issues where negating a signed integer in C would trigger undefined behavior. This fixes issues when dividing with bignums and list_to_integer.

Own Id: OTP-12290

When flushing output to stdout on windows, the emulator could sometimes hang indefinitely waiting for the flush to complete. This has been fixed.

Own Id: OTP-12291

Fix so that non-smp emulators with dirty scheduler support shows the correct number of dirty schedulers when calling erlang:system_info(system_version).

Own Id: OTP-12295

Add nif_version to erlang:system_info/1 in order to get the NIF API version of the runtime system in a way similar to driver_version.

Own Id: OTP-12298

Fix bug that could cause the return value from dirty NIF with zero arity to be treated as garbage, leading to VM crash.

Own Id: OTP-12300

Improve allocation carrier migration search logic. This will reduce the risk of failed migrations that could lead to excess memory consumption. It will also improve smp performance due to reduced memory contention on the migration pool.

Own Id: OTP-12323

### Improvements and New Features

Introduced support for eager check I/O.

By default eager check I/O will be disabled, but this will most likely be changed in OTP 18. When eager check I/O is enabled, schedulers will more frequently check for I/O work. Outstanding I/O operations will however not be prioritized to the same extent as when eager check I/O is disabled.

Eager check I/O can be enabled using the erl command line argument: +secio true

Characteristics impact when enabled:

Lower latency and smoother management of externally triggered I/O operations. A slightly reduced priority of externally triggered I/O operations.

Own Id: OTP-12117

Fix erts .app-file

Own Id: OTP-12189

Add configure option --with-ssl-incl=PATH to support OpenSSL installations with headers and libraries at different places.

Own Id: OTP-12215 Aux Id: seq12700

Optimization of atomic memory operations with release barrier semantics on 32-bit PowerPC when using the implementation included in OTP.

Own Id: OTP-12250

Minor adjustment of scheduler activation code making sure that an activation of a scheduler is not prevented by its run-queue being non-empty. (Thanks to Songlu Cai)

Own Id: OTP-12287

Improved support for atomic memory operations provided by the libatomic_ops library. Most importantly support for use of native double word atomics when implemented by libatomic_ops (for example, implemented for ARM).

The $ERL_TOP/HOWTO/INSTALL.md document now also more clearly describes when you want to build together with a libatomic_ops installation.

Own Id: OTP-12302

Add configure option --with-ssl-rpath to control which runtime library path to use for dynamic linkage toward OpenSSL.

Own Id: OTP-12316 Aux Id: seq12753

Added systemd notify support to epmd

Own Id: OTP-12321

## Erts 6.2.1

### Fixed Bugs and Malfunctions

Fix bug when an migrated empty memory carrier is reused just before it should be destroyed by the thread that created it.

Own Id: OTP-12249

Repair run_erl terminal window size adjustment sent from to_erl. This was broken in OTP 17.0 which could lead to strange cursor behaviour in the to_erl shell.

Own Id: OTP-12275 Aux Id: seq12739

## Erts 6.2

### Fixed Bugs and Malfunctions

General documentation updates.

Own Id: OTP-12052

A bug in the VM code implementing sending of signals to ports could cause the receiving port queue to remain in a busy state forever. When this state had been reached, processes sending command signals to the port either got suspended forever, or, if the nosuspend feature was used, always failed to send to the port. This bug was introduced in ERTS version 5.10.

In order for this bug to be triggered on a port, one had to at least once utilize the nosuspend functionality when passing a signal to the port. This by either calling

port_command(Port, Data, [nosuspend | Options]), erlang:send(Port, {PortOwner, {command, Data}}, [nosuspend | Options]), erlang:send_nosuspend(Port, {PortOwner, {command, Data}}), or erlang:send_nosuspend(Port, {PortOwner, {command, Data}}, Options).

Thanks Vasily Demidenok for reporting the issue, and Sergey Kudryashov for providing a testcase.

Own Id: OTP-12082 Aux Id: OTP-10336

Fix size overflow bug at memory allocation. A memory allocation call, with an insane size close to the entire address space, could return successfully as if it had allocated just a few bytes. (Thanks to Don A. Bailey for reporting)

Own Id: OTP-12091

Fix various issues where negating a signed integer would trigger undefined behaviour. This fixes issues in the enif_make_int64 interface and some edge cases inside the erlang runtime system.

Own Id: OTP-12097

The documentation erroneously listed the +swct command line argument under +sws.

Own Id: OTP-12102 Aux Id: OTP-10994

Profiling messages could be delivered out of order when profiling on runnable_procs and/or runnable_ports using erlang:system_profile/2. This bug was introduced in ERTS version 5.10.

Own Id: OTP-12105 Aux Id: OTP-10336

Various logging fixes, including: Add run queue index to the process dump in crash dumps.
Add thread index to enomem slogan when crashing.
Remove error logger message for sending messages to old instances of the same node.

Own Id: OTP-12115

Fix compiler warnings reported by LLVM

Own Id: OTP-12138

Correct conversion of MIN_SMALL by list_to_integer/1 and binary_to_integer/1. The bug produced an unnormalized bignum which can cause strange behavior such as comparing different to a correct MIN_SMALL integer. The value MIN_SMALL is -(1 bsl 27) = -134217728 on a 32-bit VM and -(1 bsl 59) = -576460752303423488 on a 64-bit VM. (Thanks to Jesper Louis Andersen, Mikael Pettersson and Anthony Ramine for report, patch and optimization suggestion)

Own Id: OTP-12140

Fix bug in term_to_binary that reallocates binary with inconsistent size information. Bug has never been confirmed to be the cause of any faulty behavior.

Own Id: OTP-12141

Real_path method used while prim loading archive files was not taking into account the fact that windows directory symlinks can be across different drives.

Own Id: OTP-12155

### Improvements and New Features

Add log2 histogram to lcnt for lock wait time

Own Id: OTP-12059

Introduced enif_schedule_nif() to the NIF API.

The enif_schedule_nif() function allows a long-running NIF to be broken into separate NIF invocations without the help of a wrapper function written in Erlang. The NIF first executes part of the long-running task, then calls enif_schedule_nif() to schedule a NIF for later execution to continue the task. Any number of NIFs can be scheduled in this manner, one after another. Since the emulator regains control between invocations, this helps avoid problems caused by native code tying up scheduler threads for too long.

The enif_schedule_nif() function also replaces the enif_schedule_dirty_nif() in the experimental dirty NIF API. Note that the only incompatible changes made are in the experimental dirty NIF API.

See the NIF documentation for more information.

Thanks to Steve Vinoski.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-12128

## Erts 6.1.2

### Fixed Bugs and Malfunctions

OTP-11850 fixed filelib:wildcard/1 to work with broken symlinks. This correction, however, introduced problems since symlinks were no longer followed for functions like filelib:ensure_dir/1, filelib:is_dir/1, filelib:file_size/1, etc. This is now corrected.

Own Id: OTP-12054 Aux Id: seq12660

## Erts 6.1.1

### Fixed Bugs and Malfunctions

Fixed ETHR_FORCE_INLINE which caused the build to break on some platforms without adequate thread support (VxWorks).

Own Id: OTP-12010

## Erts 6.1

### Fixed Bugs and Malfunctions

The documentation for spawn_opt/5 now has a note mentioning that the monitor option is not supported.

Own Id: OTP-11849

Fix broken system monitoring of large_heap for non-smp VM. No message for large_heap was ever sent on non-smp VM. Bug exist since R16B.

Own Id: OTP-11852

The emulator without SMP support crashed when passing a message to a process without enough heap space for the message. This bug was introduced in erts-6.0.

Own Id: OTP-11887 Aux Id: OTP-11388

Fix race between ETS table deletion and unfixation that could cause VM crash. The race could happen between a terminating process that does not own the table but has a fixation on it and another process that deletes the table (maybe the owner terminating) at the same time. Bug existed since R15B02.

Own Id: OTP-11892

The string following the -eval option when invoking erl would not be properly translated from UTF-8 to a list of Unicode characters (as would the arguments for -run).

That bug would cause the build of Erlang/OTP to fail when building in a directory whose pathname contained non-US ASCII characters encoded in UTF-8. (Thanks to Eric Pailleau for reporting this bug.)

Own Id: OTP-11916

Fix erts_debug:size/1 to handle Map sizes

Own Id: OTP-11923

Removed erlang:bitstr_to_list/1 and erlang:list_to_bitstr/1. They were added by mistake, and have always raised an undefined exception when called.

Own Id: OTP-11942

Fixed compilation using mingw-w64 on Windows.

Thanks to Jani Hakala.

Own Id: OTP-11945

The git sha is no longer printed in the shell start header when erlang is built from a tagged git release.

Own Id: OTP-11961

Fixed a bug where send trace events were erroneously dropped when the send was done to a registered process. This bug was introduced in R16B.

Own Id: OTP-11968

### Improvements and New Features

The following native functions now bump an appropriate amount of reductions and yield when out of reductions:

erlang:binary_to_list/1 erlang:binary_to_list/3 erlang:bitstring_to_list/1 erlang:list_to_binary/1 erlang:iolist_to_binary/1 erlang:list_to_bitstring/1 binary:list_to_bin/1

Characteristics impact:

Performance The functions converting from lists got a performance loss for very small lists, and a performance gain for very large lists. Priority Previously a process executing one of these functions effectively got an unfair priority boost. This priority boost depended on the input size. The larger the input was, the larger the priority boost got. This unfair priority boost is now lost.

Own Id: OTP-11888

The systemd features of epmd have been removed from epmd by default. To enable them you have to build erlang with the configure option --enable-systemd.

Own Id: OTP-11921

Removed Erlang wrapper code used when calling binary_to_term/1, and binary_to_term/2. This improves the performance of these BIFs especially when they are called with small binaries as input.

Own Id: OTP-11931

Add erlang:system_info(tolerant_timeofday), an API to check whether compensation for sudden changes of system time is enabled or not.

Own Id: OTP-11970

## Erts 6.0.1

### Fixed Bugs and Malfunctions

Fix broken system monitoring of large_heap for non-smp VM. No message for large_heap was ever sent on non-smp VM. Bug exist since R16B.

Own Id: OTP-11852

Fixed type spec of erlang:system_info/1.

Own Id: OTP-11859 Aux Id: OTP-11615

## Erts 6.0

### Fixed Bugs and Malfunctions

The option dupnames did not work as intended in re. When looking for names with {capture, [Name, ...]}, re:run returned a random instance of the match for that name, instead of the leftmost matching instance, which was what the documentation stated. This is now corrected to adhere to the documentation. The option {capture,all_names} along with a re:inspect/2 function is also added to further help in using named subpatterns.

Own Id: OTP-11205

Allow loading of NIF library with unicode path name

Own Id: OTP-11408

Allow loading of driver with unicode path name

Own Id: OTP-11549

Fixed a bug where starting Erlang without having an open stdin on fd 0 would sometimes deadlock the emulator when terminating.

Own Id: OTP-11558

The option '-names' in epmd now works on Windows (Thanks to Johannes Weißl)

Own Id: OTP-11565

Correction of the examples in escript documentation. (Thanks to Pierre Fenoll).

Own Id: OTP-11577

Fix bs_get_integer instruction

The instruction bs_get_integer could unnecessarily trigger a garbage collection in failure cases which is unwanted or outright dangerous.

Ex:

<<X:Sz,_/bits>> = <<"some binary">>

Previously, if Sz induced X to a bignum it would reserved memory size this on the heap via a garbage collection before checking if the size could actually match.

It will now check the binary size before triggering a collection.

Own Id: OTP-11581

Remove heap space overestimation in binary_to_term (and remote message reception) for integers in the intervals [-2147483648,-1] and [256,2147483647] on 64-bit emulators.

Own Id: OTP-11585

Add support for detecting the separate tinfo library from ncurses (Thanks to Dirkjan Ochtman)

Own Id: OTP-11590

Deprecation warning for system_flag(cpu_topology) has been extended for removal in OTP 18 (Thanks to Steve Vinoski for the update)

Own Id: OTP-11602

Documentation improvement regarding some awkward wording around the +spp flag. (Thanks to Brian L. Troutwine )

Own Id: OTP-11607

Fixed bug where sendfile would return the wrong error code for a remotely closed socket if the socket was in passive mode. (Thanks to Vincent Siliakus for reporting the bug.)

Own Id: OTP-11614

Increase garbage collection tenure rate

The garbage collector tries to maintain the previous heap block size during a minor gc, i.e. 'need' is not utilized in determining the size of the new heap, instead it relies on tenure and garbage to be sufficiently large.

In instances during intense growing with exclusively live data on the heap coupled with delayed tenure, fullsweeps would be triggered directly after a minor gc to make room for 'need' since the new heap would be full.

To remedy this, the tenure of terms on the minor heap will always happen (if it is below the high watermark) instead of every other minor gc.

Characteristics Impact: Reduced CPU-time spent in garbage collection but may infer delays in collecting garbage from the heap. Tweak 'fullsweep_after' options to increase gc pressure if needed.

Own Id: OTP-11617

Fix bug when comparing integers with floats larger than 2^992. The bug could potentially cause memory corruption on 32-bit emulators.

Own Id: OTP-11618

Cross-compilation fixes for TileraMDE-3.0.1.125620

Own Id: OTP-11635

sendfile no longer uses async threads by default

This has been done because a slow client attack is possible if the async thread pool is used. The scenario is:

Client does a request for a file and then slowly receives the file one byte at a time. This will eventually fill the async thread pool with blocking sendfile operations and thus starving the vm of all file operations.

If you still want to use the async threads pool for sendfile an option to enable it has been introduced.

Thanks to Christopher Faulet for identifying this vulnerability.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11639

Do proper rollback of calls to enif_open_resource_type when load/upgrade callbacks of NIF library return failure.

Own Id: OTP-11722

Changed the default configuration when configuring with $ERL_TOP/configure to be the same as when configuring with $ERL_TOP/otp_build configure.

Previously floating point exceptions got enabled by default on Linux when HiPE was enabled when configuring with $ERL_TOP/configure, but not when configuring with $ERL_TOP/otp_build configure. The default is now in both cases not to use floating point exceptions since there still exist unresolved issues with floating point exceptions on Linux.

For more information see $ERL_TOP/HOWTO/INSTALL.md.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11723

A comment in erl_db_tree.c no longer differ from the code. (Thanks to Cobus Carstens)

Own Id: OTP-11793

Fix epmd debug functionality for VxWorks (Thanks to Jay True)

Own Id: OTP-11808

Use closefrom/2 when available in child_setup (Thanks to Rick Reed and Anthony Ramine)

Own Id: OTP-11809

Fix dtrace/systemtap bug where the probe arguments would be concatenated due to faulty length calculation.

Thanks to Michal Ptaszek and Scott Lystig Fritchie

Own Id: OTP-11816

It is now better documented that the +fn* flags to erl also affect how command line parameters and environment variables are read. (Thanks to Vlad Dumitrescu)

Own Id: OTP-11818

### Improvements and New Features

Options to set match_limit and match_limit_recursion are added to re:run. The option report_errors is also added to get more information when re:run fails due to limits or compilation errors.

Own Id: OTP-10285

Dialyzer's unmatched_return warnings have been corrected.

Own Id: OTP-10908

A common case is to wrap an argument to list_to_binary/1 in a list to ensure conversion can happen even though the argument may already be a binary. Take special care of this case and do not copy binary.

Impact: May cause incompatibility since a single binary is no longer copied. Use binary:copy/1,2 instead.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11082

Make erlang:open_port/2 spawn and spawn_executable handle unicode.

Own Id: OTP-11105

Handle unicode (widestring) in erl, erlc, heart, etc on windows.

Own Id: OTP-11135

The version of the PCRE library Used by Erlang's re module is raised to 8.33 from 7.6. This means, among other things, better Unicode and Unicode Character Properties support. New options connected to PCRE 8.33 are also added to the re module (ucd, notempty_atstart, no_start_optimize). PCRE has extended the regular expression syntax between 7.6 and 8.33, why this imposes a potential incompatibility. Only very complicated regular expressions may be affected, but if you know you are using obscure features, please test run your regular expressions and verify that their behavior has not changed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11204

Filenames containing UTF-8 encoded characters can now be handled by erlc.

If you have set the ERLC_EMULATOR environment variable, note that erlc in OTP 17 will only work with erl in OTP 17 since the protocol between the erlc program and the erl_compile module has changed.

Own Id: OTP-11248

By giving --enable-static-{nifs,drivers} to configure it is now possible to statically linking of nifs and drivers to the main Erlang VM binary. At the moment only the asn1 and crypto nifs of the Erlang/OTP nifs and drivers have been prepared to be statically linked. For more details see the Installation Guide in the System documentation.

Own Id: OTP-11258

Erlang/OTP has been ported to the realtime operating system OSE. The port supports both smp and non-smp emulator. For details around the port and how to started see the User's Guide in the ose application.

Note that not all parts of Erlang/OTP has been ported.

Notable things that work are: non-smp and smp emulators, OSE signal interaction, crypto, asn1, run_erl/to_erl, tcp, epmd, distribution and most if not all non-os specific functionality of Erlang.

Notable things that does not work are: udp/sctp, os_mon, erl_interface, binding of schedulers.

Own Id: OTP-11334

Add the {active,N} socket option for TCP, UDP, and SCTP, where N is an integer in the range -32768..32767, to allow a caller to specify the number of data messages to be delivered to the controlling process. Once the socket's delivered message count either reaches 0 or is explicitly set to 0 with inet:setopts/2 or by including {active,0} as an option when the socket is created, the socket transitions to passive ({active, false}) mode and the socket's controlling process receives a message to inform it of the transition. TCP sockets receive {tcp_passive,Socket}, UDP sockets receive {udp_passive,Socket} and SCTP sockets receive {sctp_passive,Socket}.

The socket's delivered message counter defaults to 0, but it can be set using {active,N} via any gen_tcp, gen_udp, or gen_sctp function that takes socket options as arguments, or via inet:setopts/2. New N values are added to the socket's current counter value, and negative numbers can be used to reduce the counter value. Specifying a number that would cause the socket's counter value to go above 32767 causes an einval error. If a negative number is specified such that the counter value would become negative, the socket's counter value is set to 0 and the socket transitions to passive mode. If the counter value is already 0 and inet:setopts(Socket, [{active,0}]) is specified, the counter value remains at 0 but the appropriate passive mode transition message is generated for the socket.

Thanks to Steve Vinoski

Own Id: OTP-11368

A new optional scheduler utilization balancing mechanism has been introduced. For more information see the +sub command line argument.

Characteristics impact: None, when not enabled. When enabled, changed timing in the system, normally a small overhead due to measuring of utilization and calculating balancing information. On some systems, such as old Windows systems, the overhead can be quite substantial. This time measurement overhead highly depend on the underlying primitives provided by the OS.

Own Id: OTP-11385

A call to either the garbage_collect/1 BIF or the check_process_code/2 BIF may trigger garbage collection of another processes than the process calling the BIF. The previous implementations performed these kinds of garbage collections without considering the internal state of the process being garbage collected. In order to be able to more easily and more efficiently implement yielding native code, these types of garbage collections have been rewritten. A garbage collection like this is now triggered by an asynchronous request signal, the actual garbage collection is performed by the process being garbage collected itself, and finalized by a reply signal to the process issuing the request. Using this approach processes can disable garbage collection and yield without having to set up the heap in a state that can be garbage collected.

The garbage_collect/2, and check_process_code/3 BIFs have been introduced. Both taking an option list as last argument. Using these, one can issue asynchronous requests.

code:purge/1 and code:soft_purge/1 have been rewritten to utilize asynchronous check_process_code requests in order to parallelize work.

Characteristics impact: A call to the garbage_collect/1 BIF or the check_process_code/2 BIF will normally take longer time to complete while the system as a whole wont be as much negatively effected by the operation as before. A call to code:purge/1 and code:soft_purge/1 may complete faster or slower depending on the state of the system while the system as a whole wont be as much negatively effected by the operation as before.

Own Id: OTP-11388 Aux Id: OTP-11535, OTP-11648

Cleanup 'Buckets' and 'Time left' fields in crashdump to ease parsing.

Own Id: OTP-11419

Add sync option to file:open/2.

The sync option adds the POSIX O_SYNC flag to the open system call on platforms that support the flag or its equivalent, e.g., FILE_FLAG_WRITE_THROUGH on Windows. For platforms that don't support it, file:open/2 returns {error, enotsup} if the sync option is passed in. Thank to Steve Vinoski and Joseph Blomstedt

Own Id: OTP-11498

erlang:binary_to_term will now cost an appropriate amount of reductions and will interrupt (yield) for reschedule if the term is big. This avoids too long schedules when binary_to_term is used. (Thanks to Svante Karlsson for the original patch)

Impact: Programs running binary_to_term on large binaries will run more smoothly, but rescheduling will impact the single process performance of the BIF. Single threaded benchmarks might show degraded performance of the BIF, while general system behaviour will be improved.

Own Id: OTP-11535 Aux Id: OTP-11388

Added high resolution icon for windows. (Thanks to Daniel Goertz for the inspiration.)

Own Id: OTP-11560

Migration of memory carriers has been enabled by default on all ERTS internal memory allocators based on the alloc_util framework except for temp_alloc. That is, +M<S>acul de is default for these allocators. Note that this also implies changed allocation strategies for all of these allocators. They will all now use the "address order first fit carrier best fit" strategy.

By passing +Muacul 0 on the command line, all configuration changes made by this change will be reverted.

Characteristics impact: Improved memory characteristics with a smaller memory footprint at the expense of a quite small performance cost.

Own Id: OTP-11604 Aux Id: OTP-10279

A clarification has been added to the documentation of -on_load() in the Reference Manual that it is only recommended for loading NIF libraries.

Own Id: OTP-11611

+fnaw is now default when starting the emulator; it used to be +fnl.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11612

EEP43: New data type - Maps

With Maps you may for instance:

M0 = #{ a => 1, b => 2}, % create associations M1 = M0#{ a := 10 }, % update values M2 = M1#{ "hi" => "hello"}, % add new associations #{ "hi" := V1, a := V2, b := V3} = M2. % match keys with values

For information on how to use Maps please see Map Expressions in the Reference Manual.

The current implementation is without the following features:

No variable keys No single value access No map comprehensions

Note that Maps is experimental during OTP 17.0.

Own Id: OTP-11616

The previously deprecated driver API function driver_async_cancel() has been removed. Due to this, the driver API version has been bumped to 3.0.

Thanks to Steve Vinoski.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11628

Experimental "dirty scheduler" functionality has been introduced. In order to try the functionality out, you need to pass the command line argument --enable-dirty-schedulers to configure when building the system.

Dirty schedulers can currently only be used by NIFs on a system with SMP support. More information can be found in the erl_nif(3) documentation, the erl(1) documentation, and in the git commit comment of commit 'c1c03ae4ee50e58b7669ea88ec4d29c6b2b67c7b'.

Note that the functionality is experimental, and not supported. This functionality will be subject to backward incompatible changes. You should not enable the dirty scheduler functionality on production systems. It is only provided for testing.

Thanks to Steve Vinoski.

Own Id: OTP-11629

Improve reduction cost and yielding of term_to_binary. The reduction cost is increased and garbage collection is disabled during yield.

Impact: Improves system responsiveness when term_to_binary is called with large terms without significant degradation of single threaded performance.

Own Id: OTP-11648 Aux Id: OTP-11388

By default, the system's version of zlib will be used, provided its version is 1.2.4 or higher; otherwise the built-in zlib will be used. The built-in version of zlib has been bumped to 1.2.8. (Use the --enable-builtin-zlib option to configure to force the use of the built-in zlib.)

Own Id: OTP-11669

The default float encoding in binary_to_term and external_size has been changed to use minor_mode 1 instead of 0.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11738

Introduced the configure option --with-assumed-cache-line-size=SIZE. For more information see $ERL_TOP/HOWTO/INSTALL.md.

Own Id: OTP-11742

Halfword emulator is marked as deprecated. It still works as before but is planned to be removed in a future major release.

Own Id: OTP-11777

The external format for Maps has changed in a way that is not compatible with the format used in OTP 17.0-rc1 and OTP 17.0-rc2.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11782

Fixed faulty make dependency that would make some make versions fail while building gen_git_version.mk.

Own Id: OTP-11784

Introduced functionality for allowing old drivers and NIF libraries to be loaded during a transition period. For more information see the version management section in the erl_driver(3) documentation and the version management section in the erl_nif(3) documentation.

Own Id: OTP-11799

Support file paths longer than 259 characters on Windows. Long absolute paths are automatically converted to UNC format with a \\?\ prefix which is the only way to represent long paths. The 259 character limit still applies for individual file names, relative paths and the current working directory.

Own Id: OTP-11813

Document that escript:create/2 also accepts a 3-elements tuple containing files and zip:create/3 options to build a zip file.

Thanks to Pierre Fenoll

Own Id: OTP-11827

Add systemd socket activation for epmd.

Thanks to Matwey V. Kornilov

Own Id: OTP-11829

## Erts 5.10.4.1

### Known Bugs and Problems

When using gen_tcp:connect and the fd option with port and/or ip, the port and ip options were ignored. This has been fixed so that if port and/or ip is specified together with fd a bind is requested for that fd. If port and/or ip is not specified bind will not be called.

Own Id: OTP-12061

## Erts 5.10.4

### Fixed Bugs and Malfunctions

When normalizing paths, erl_prim_loader would always convert backslash to forward slash. This is correct on Windows, but not on other operating systems. erl_prim_loader now checks which OS is running before performing this conversion.

Own Id: OTP-11170

Fixed syslog defines and defined LOG_ERR for systems without syslog.h. Thanks to Matt Lewandowsky.

Own Id: OTP-11349

Check all pattern arguments passed to binary:matches/2. Thanks to Mike Sassak.

Own Id: OTP-11350

Fix two small silent rules omissions. Thanks to Anthony Ramine.

Own Id: OTP-11351

Teach configure to detect if posix_memalign cannot align to more than the system page size.

For cross-compiled systems a new environment variable called erl_xcomp_posix_memalign has been introduced to indicate whether posix_memalign should be used.

Own Id: OTP-11371

Fix bsr bug occurring when shifting a huge number a huge number of bits to the right. Thanks to Lars Hesel Christensen.

Own Id: OTP-11381

Fix memory leak for distributed monitors

Own Id: OTP-11410

Fix various typos in erts, kernel and ssh. Thanks to Martin Hässler.

Own Id: OTP-11414

Crashdumps initiated by out-of-memory on process spawn could cause the beam to segfault during crashdump writing due to invalid pointers.

The pointers are invalid since the process creation never finished. This fix removes these processes from the printouts. Reported by Richard Carlsson.

Own Id: OTP-11420

Crash dumps from 64-bit Erlang machines would have all memory addresses truncated to 32 bits, which could cause trouble inspecting processes message queues and stacks in the crashdump viewer.

Own Id: OTP-11450

Threads other than schedulers threads could make thread unsafe accesses when support for migration of memory carriers had been enabled, i.e., when the +M<S>acul command line flag had been passed to erl. This could cause corruption of the VMs internal state.

This bug was introduced in erts-5.10.2 when the support for migration of memory carriers was introduced.

Own Id: OTP-11456 Aux Id: OTP-10279

Fix bug in binary_to_term for invalid bitstrings and very large binaries (>2Gb).

Own Id: OTP-11479

Under rare circumstances a process calling inet:close/1, gen_tcp:close/1, gen_udp:close/1, or gen_sctp:close/1 could hang in the call indefinitely.

Own Id: OTP-11491

Fix bug that could cause a 32-bit emulator to always crash at start (since R16B01) depending on the alignment of static data in the beam executable.

Own Id: OTP-11496

Fix benign bugs regarding bitstring compare. Only a nuisance for debug and valgrind VM.

Own Id: OTP-11501

Silence warnings (Thanks to Anthony Ramine)

Own Id: OTP-11517

The default wordsize of the emulator (beam) is now determined by compiler default on Mac OSX (Darwin). This was previously forced to 32bits by the configure script unless otherwise specified.

Own Id: OTP-11521

### Improvements and New Features

A new memory allocation feature called "super carrier" has been introduced. The super carrier feature can be used in different ways. It can for example be used for pre-allocation of all memory that the runtime system should be able to use.

By default the super carrier is disabled. It is enabled by passing the +MMscs <size in MB> command line argument. For more information see the documentation of the +MMsco, +MMscrfsd, +MMscrpm, +MMscs, +MMusac, and, +Mlpm command line arguments in the erts_alloc(3) documentation.

Since it is disabled by default there should be no impact on system characteristics if not used.

This change has been marked as a potential incompatibility since the returned list when calling erlang:system_info({allocator, mseg_alloc}) now also include an {erts_mmap, _} tuple as one element in the list.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11149

Added erlang:system_info(ets_limit) to provide a way to retrieve the runtime's maximum number of ETS tables. Thanks to Steve Vinoski

Own Id: OTP-11362

Add new BIF os:unsetenv/1 which deletes an environment variable. Thanks to Martin Hässler.

Own Id: OTP-11446

Introduced a new guarantee regarding exit signals from ports:

If the process calling one of the synchronous port BIFs listed below is linked to the port identified by the first argument, and the port exits before sending the result of the port operation, the exit signal issued due to this link will be received by the processes before the BIF returns, or fail with an exception due to the port not being open.

The synchronous port BIFs are:

port_close/1 port_command/2 port_command/3 port_connect/2 port_control/3 erlang:port_call/3 erlang:port_info/1 erlang:port_info/2

Note that some ports under certain circumstances unlink themselves from the calling process before exiting, i.e. even though the process linked itself to the port there might be no link triggering an exit signal.

Characteristics impact: The return or exception from the synchronous port BIF will be delayed if the port simultaneously exit due to some issue unrelated to the outstanding synchronous port BIF call. In all other cases characteristics are unchanged.

Own Id: OTP-11489

## Erts 5.10.3.1

### Improvements and New Features

Memory allocators will be able to create sys_alloc carriers as fallback, if mseg_alloc cannot create more carriers, on systems with posix_memalign() support. This is similar to how it worked in pre-R16 releases.

Windows systems will create carriers using _aligned_malloc() and can by this use the new optimized allocator header scheme introduced in R16 on other platforms.

Own Id: OTP-11318

## Erts 5.10.3

### Fixed Bugs and Malfunctions

The documentation of predefined types and built-in types has been corrected.

Own Id: OTP-11090

Fix changing terminal parameters in to_erl

Change the behaviour of to_erl to use TCSADRAIN instead of TCSANOW when changing terminal parameters. This makes the serial driver wait for the output queues to be empty before applying the terminal parameter change. Thanks to Stefan Zegenhagen.

Own Id: OTP-11206

The default value of {flush, boolean()} in erlang:halt/2 is documented to be 'true' if the status is an integer. The implementation behaviour was reversed. The Implementation is now corrected to adhere to the documentation. Thanks to Jose Valim for reporting the error.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11218

Fix serious race bug in R16B01 that could cause PID mix-ups when a lot of processes were spawned and terminated in a very rapid pace on an SMP emulator with at least two scheduler threads.

Own Id: OTP-11225

Validating a trace pattern with the option silent no longer incorrectly enables/disables the silent option of the calling process.

Own Id: OTP-11232

Fixed a bug where GCC 4.8 and later use a more aggressive loop optimization algorithm that broke some previously working code in the efile driver. Thanks to Tomas Abrahamsson for reporting this issue.

Own Id: OTP-11246

Fixed bug when printing memory allocator acul option in crash dump.

Own Id: OTP-11264

Opening a new compressed file on Windows could in rare (random) cases result in {error,eisdir} or other error codes although it should have succeeded. This is now corrected.

Own Id: OTP-11265

Fixed a race condition when closing a trace port that would cause the emulator to crash.

Own Id: OTP-11290

### Improvements and New Features

There is a new somewhat experimental socket option 'netns' that can set the network namespace for a socket on Linux:es where it is supported. See the documentation.

Own Id: OTP-11157

New allocator strategy aoffcbf (address order first fit carrier best fit). Supports carrier migration but with better CPU performance than aoffcaobf.

Own Id: OTP-11174

Introduced functionality for inspection of system and build configuration.

Own Id: OTP-11196

Fix matching of floating point middle-endian machines. Thanks to Johannes Weissl.

Own Id: OTP-11201

Fix compile error on ARM and GCC versions greater than 4.1.0. Thanks to Johannes Weissl.

Own Id: OTP-11214

run_erl: Redirect standard streams to /dev/null. Thanks to Johannes Weissl.

Own Id: OTP-11215

Misc. corrections in documentation for erl_driver. Thanks to Giacomo Olgeni.

Own Id: OTP-11227

Fix documentation regarding binary_part.

Own Id: OTP-11239

Make edlin understand a few important control keys. Thanks to Stefan Zegenhagen.

Own Id: OTP-11251

Export type zlib:zstream/0. Thanks to Loic Hoguin.

Own Id: OTP-11278

Add erl option to set schedulers by percentages.

For applications where measurements show enhanced performance from the use of a non-default number of emulator scheduler threads, having to accurately set the right number of scheduler threads across multiple hosts each with different numbers of logical processors is difficult because the erl +S option requires absolute numbers of scheduler threads and scheduler threads online to be specified.

To address this issue, add a +SP option to erl, similar to the existing +S option but allowing the number of scheduler threads and scheduler threads online to be set as percentages of logical processors configured and logical processors available, respectively. For example, "+SP 50:25" sets the number of scheduler threads to 50% of the logical processors configured, and the number of scheduler threads online to 25% of the logical processors available. The +SP option also interacts with any settings specified with the +S option, such that the combination of options "+S 4:4 +SP 50:50" (in either order) results in 2 scheduler threads and 2 scheduler threads online.

Thanks to Steve Vinoski

Own Id: OTP-11282

Extend erl_driver interface with lock names

Lock and thread names are already a feature in the driver interface. This extension will let developers read these names which eases debugging.

Own Id: OTP-11303

Fix incorrect values returned by integer_to_binary/2. Thanks to Juan Jose Comellas.

Own Id: OTP-11311

Fix system_flag scheduling_statistics - disable . Thanks to Steve Vinoski.

Own Id: OTP-11317

The documentation of predefined types has been corrected Thanks to Kostis Sagonas.

Own Id: OTP-11321

## Erts 5.10.2

### Fixed Bugs and Malfunctions

A bug in prim_inet has been corrected. If the port owner was killed at a bad time while closing the socket port the port could become orphaned hence causing port and socket leaking. Reported by Fred Herbert, Dmitry Belyaev and others.

Own Id: OTP-10497 Aux Id: OTP-10562

Compilation fixes for NetBSD. Thanks to YAMAMOTO Takashi.

Own Id: OTP-10941

Fixed a race condition when using delayed_write when writing to a file which would cause the same data to be written multiple times.

Own Id: OTP-10984

Fix small memory leak from tracing with option meta.

Own Id: OTP-10997

Correct typo in erlsrv usage. Thanks to Bryan Hunter

Own Id: OTP-11002

ct_run: delete unused function. Thanks to Tuncer Ayaz.

Own Id: OTP-11003

Corrections to run_erl/to_erl handshake behaviour.

Own Id: OTP-11012

Fix typo in type: erlang:process_info_item(). Thanks to Andrew Tunnell-Jones.

Own Id: OTP-11024

Fix src/dest overlap issue in ttsl driver. Thanks to Steve Vinoski.

Own Id: OTP-11064

When sending to a port using erlang:send(Port, Msg, [nosuspend]), the send operation was performed synchronously. This bug has now been fixed.

Own Id: OTP-11076 Aux Id: OTP-10336

When converting a faulty binary to a list with unicode:characters_to_list, the error return value could contain a faulty "rest", i.e. the io_list of characters that could not be converted was wrong. This happened only if input was a sub binary and conversion was from utf8. This is now corrected.

Own Id: OTP-11080

Runtime system could crash when reporting stale driver_select().

Own Id: OTP-11084

Fix lock order violation for memory instrumentation (+Mim, +Mis, +Mit).

Own Id: OTP-11085

Fixed some compilation warnings on miscellaneous platforms. Thanks to Anthony Ramine.

Own Id: OTP-11086

Fixed issue when flushing i/o during shutdown on windows where the Erlang VM would sometime hang due to a race condition.

Own Id: OTP-11096

Fixed issue where repeated calls to erlang:nodes() could cause unnecessary contention in the dist_table lock.

Own Id: OTP-11097

Properly guard WIDE_TAG use with HAVE_WCWIDTH in ttsl_drv. Thanks to Anthony Ramine

Own Id: OTP-11106

Fix some Makefile rules that didn't support silent rules. Thanks to Anthony Ramine.

Own Id: OTP-11111

Fix receive support in erl_eval with a BEAM module. Thanks to Anthony Ramine.

Own Id: OTP-11137

erlang:now() could suddenly jump ~24 days into the future on Windows. This is now corrected. Thanks to Garret Smith for reporting and testing fixes.

Own Id: OTP-11146

erlang:term_to_binary will now cost an appropriate amount of reductions and will interrupt (yield) for reschedule if the term is big. This avoids too long schedules when term_to_binary is used.

Impact: Programs running term_to_binary on large terms will run more smothly, but rescheduling will impact the single process performance of the BIF. Single threaded benchmarks will show degraded performance of the BIF when called with very large terms, while general system behaviour will be improved. The overhead for allowing restart and reduction counting also degrades local performance of the BIF with between 5% and 10% even for small terms.

Own Id: OTP-11163

### Improvements and New Features

Replaced the lock protecting gathering of garbage collection statistics with a lock-free solution.

Own Id: OTP-10271 Aux Id: kunagi-108 [04c5410f-9cc4-4696-8639-36bf98686c7a-7]

Support for migration of memory carriers between memory allocator instances has been introduced.

By default this feature is not enabled and do not effect the characteristics of the system. When enabled it has the following impact on the characteristics of the system:

Reduced memory footprint when the memory load is unevenly distributed between scheduler specific allocator instances. Depending on the default allocaton strategy used on a specific allocator there might or might not be a slight performance loss. When enabled on the fix_alloc allocator, a different strategy for management of fix blocks will be used. The information returned from erlang:system_info({allocator, A}), and erlang:system_info({allocator_sizes, A}) will be slightly different when this feature has been enabled. An mbcs_pool tuple will be present giving information about abandoned carriers, and in the fix_alloc case no fix_types tuple will be present.

For more information, see the documentation of the +M<S>acul command line argument.

Own Id: OTP-10279

Change specs for spawn_opt to use the process_level() type declaration instead of re-defining it in various places. Thanks to Kostis Sagonas.

Own Id: OTP-11008

Postscript files no longer needed for the generation of PDF files have been removed.

Own Id: OTP-11016

Erlang source files with non-ASCII characters are now encoded in UTF-8 (instead of latin1).

Own Id: OTP-11041 Aux Id: OTP-10907

Optimization of simultaneous inet_db operations on the same socket by using a lock free implementation.

Impact on the characteristics of the system: Improved performance.

Own Id: OTP-11074

The high_msgq_watermark and low_msgq_watermark inet socket options introduced in OTP-R16A could only be set on TCP sockets. These options are now generic and can be set on all types of sockets.

Own Id: OTP-11075 Aux Id: OTP-10336

A new better algorithm for management of the process, and port tables has been introduced.

Impact on the characteristics of the system:

The new algorithm ensures that both insert and delete operations can be made in O(1) time complexity. Previously used algorithm either caused insert or delete to be O(N). The new algorithm will also ensure that reuse of identifiers will be less frequent than when the old algorithm was used. Previously used algorithm ensured that the latest created identifier compared as the largest when comparing two identifiers of the same type that had been created on the same node as long as no identifiers had been reused. Since identifiers can be reused quite fast, one has never been able to rely on this property. Due to the introduction of this new algorithm this property will not hold even if no identifiers has been reused yet. This could be considered as an incompatibility.

Due to the above mensioned potential incompatibility, it will still be possible to enable the old algorithm for some time. The command line argument +P legacy will enable the old algorithm on the process table, and +Q legacy will do the same for the port table. These command line arguments are however deprecated as of their introduction and have been scheduled for removal in OTP-R18.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11077

Support wide characters in the shell through wcwidth(). Thanks to Anthony Ramine. Reported by Loïc Hoguin.

Own Id: OTP-11088

Added total used memory for each process in erlang crash dumps.

Own Id: OTP-11098

Added support for hipe on Raspberry Pi (armv6l). Thanks to Klaus Alfert.

Own Id: OTP-11125

Remove 'query' from the list of reserved words in docs. Thanks to Matthias Endler and Loïc Hoguin.

Own Id: OTP-11158

Lift static limitation (FD_SETSIZE) for file descriptors on Mac OS X. (Thanks to Anthony Ramine)

Own Id: OTP-11159

### Known Bugs and Problems

Miscellaneous native code in OTP misbehave either due to lengthy execution, or due to not bumping reductions properly. Problems typically occur when passing huge sets of data to a misbehaving BIF. Fixing this has high priority and is being worked on, but there will remain issues like this for some time.

In order to alleviate problems with scheduling which might occur when executing misbehaving native code, the command line argument +sfwi has been introduced.

By default this feature is disabled and you are advised not to enable it if you do not encounter problems with misbehaving native code.

When enabled it has the following impact on the characteristics of the system:

Work will always be distributed between schedulers even when executing misbehaving native code. It may cause an increased amount of processes and/or ports bouncing between schedulers which in turn will cause a performance loss. It may cause reduced performance due to reduced or lost work compaction when all schedulers do not execute under full load. An increased contention on run queue locks.

Own Id: OTP-11164

## Erts 5.10.1.2

### Fixed Bugs and Malfunctions

A bug in the implementation of offline schedulers has been fixed. The bug was introduced in OTP-R16A/ERTS-5.10, and caused work-stealing between schedulers to fail. This in turn, caused work to accumulate in some run-queues. The bug was only triggered when there were offline schedulers in the system, i.e., when the amount of online schedulers was less than the total amount of schedulers. The effect of the bug got more severe the larger amount of offline schedulers the system had.

Own Id: OTP-11022 Aux Id: OTP-9892

## Erts 5.10.1.1

### Fixed Bugs and Malfunctions

The BIF is_process_alive/1 could prematurely return false while the process being inspected was terminating. This bug was introduced in ERTS-5.10.

Own Id: OTP-10926

Fix a problem in erlang:delete_element/2 where the call could corrupt one word of stack if the heap and stack met during call.

Own Id: OTP-10932

The +sws<value> and +swt<value> system flags failed if no white space were passed between the parameter and value parts of the flags. Upon failure, the runtime system refused to start.

Own Id: OTP-11000

### Improvements and New Features

Scheduler threads will now by default be less eager requesting wakeup due to certain cleanup operations. This can also be controlled using the +swct command line argument of erl(1).

Own Id: OTP-10994

## Erts 5.10.1

### Fixed Bugs and Malfunctions

Threads created internally in the runtime system by vanilla, fd, and spawn drivers on Windows systems could make thread unsafe calls to driver_select().

Own Id: OTP-10802

Threads created internally in the runtime system by the vanilla, fd, and spawn drivers on Windows systems could make unsafe memory accesses to driver data after port had terminated.

Own Id: OTP-10803

The runtime system could crash when flushing data to standard out or standard error on Windows.

Own Id: OTP-10807

Bugs due to the port optimizations introduced in erts-5.10/OTP-R16A have been fixed:

Memory leak when terminating ports Memory leak when reaching the system limit of maximum amount of concurrently existing ports Crashs due to missing, or late test of bad port handle The newly introduced driver API function erl_drv_busy_msgq_limits() could not be used by dynamically linked in drivers on Windows

Own Id: OTP-10809 Aux Id: OTP-10336

Fix {packet,httph} header capitalization for unrecognized header fields longer than 20 charachters such as Sec-Websocket-Version. The limit is simply raised from 20 to 50 characters with the hope that valid headers longer than 50 are not used.

Own Id: OTP-10824

Fix rounding issues in float_to_list/1,2. Thanks to Serge Aleynikov

Own Id: OTP-10837

Fix memory leak in file driver introduced in R16A.

Own Id: OTP-10841

A bug in an ERTS internal queue implementation could cause the loss of a wake up signal to a consumer thread. This has now been fixed.

The effect of this bug, when triggered, was often only a small or even no delay of certain operations. This since, threads often are woken due to other unrelated reasons. However, if the consumer thread was not woken due to other reasons when the bug was triggered, these operations could be left hanging, potentially for ever. Such effects seems to have been very rare, but we have on at least one occasion gotten a report about such an issue.

Operations potentially effected by this bug:

Inspection of memory allocation status The Erlang process calling erlang:memory/[0,1], or erlang:system_info({allocator|allocator_sizes, _}) could potentially hang waiting for responses from involved threads. Async thread pool jobs An async thread pool job request and/or reply could potentially be left hanging. In OTP this only effected file operations, but user implemented drivers using the async thread pool were also effected. In the file operation case, this would typically translate into an Erlang process potentially hanging on the file operation. Shutting down the runtime system Due to the issue with the async thread pool mentioned above, flushing of I/O while terminating the runtime system could also potentially hang. ETS memory deallocation Scheduled jobs handling deallocation of the main structure of an ETS table could potentially hang. This more or less only translates into minor memory leaks. Shutting down distribution The distribution shutdown phase used when manually shutting down the distribution, i.e., when calling net_kernel:stop(), could potentially hang.

Own Id: OTP-10854

OS X Snow Leopard now only uses write, as writev does not work properly on very large files.

Own Id: OTP-10858

Fixed a bug where line oriented file I/O using read_ahead was very slow for files with very large difference in line length.

Own Id: OTP-10859

In erts-5.10 (R16A) faulty hashvalues were produced for non-ASCII atoms (characters in byte-range 128..255). This has now been fixed and hashvalues conforms to previous OTP releases.

Own Id: OTP-10860

Fixes of memory accesses that might be thread unsafe when the runtime system has been linked against third-party libraries for atomic memory operations during the build. Most builds are uneffected by this bug. If triggered, the runtime system will most likely crash more or less immediately.

Own Id: OTP-10875 Aux Id: OTP-10854

Fixed a bug where it was longer possible to give the +sws proposal flag to non-smp emulators.

Own Id: OTP-10881 Aux Id: seq12258

Faulty type to bytes read for ReadFile on Windows. This could cause windows systems to misbehave. The correct type is now used.

Own Id: OTP-10890

Change default max ports for Windows to 8192. Having a too large value caused Windows to not be able to recover properly. If you want to use another value, pass +Q Value to erl or werl.

Own Id: OTP-10892

Fix rare crash on halfword vm during code loading.

Own Id: OTP-10896

### Improvements and New Features

Tuple funs (deprecated in R15B) are no longer supported.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10170

Added four new bifs, erlang:binary_to_integer/1,2, erlang:integer_to_binary/1, erlang:binary_to_float/1 and erlang:float_to_binary/1,2. These bifs work similarly to how their list counterparts work, except they operate on binaries. In most cases converting from and to binaries is faster than converting from and to lists.

These bifs are auto-imported into erlang source files and can therefore be used without the erlang prefix.

Own Id: OTP-10300 Aux Id: kunagi-74 [74]

The experimental support for packages has been removed.

Own Id: OTP-10348 Aux Id: kunagi-316 [227]

The driver API function erl_drv_consume_timeslice(), and the NIF API function enif_consume_timeslice() have been introduced.

These functions are provided in order to better support co-operative scheduling, improve system responsiveness, and to make it easier to prevent misbehaviors of the VM due to a process or port monopolizing a scheduler thread. They can be used when dividing lengthy work into a number of repeated calls without the need to use threads.

Own Id: OTP-10810

The list_to_integer/2 bif has been optimized when used with bases other than 10.

Own Id: OTP-10834 Aux Id: kunagi-74 [74]

The git commit sha of the HEAD commit is now added to the Erlang shell when compiling a non-released Erlang version.

Own Id: OTP-10838

Change caching policy for memory segment allocator. For instance, prefer sbc segments over mbc segments, caching policy is time-arrow aware, evicting older cached segments to store newer segments.

The default number of cachable segment has been increased from five to ten segments. This can be modified, same as before, with the command line option +MMmcs 5

Impact: Increased speed for processing on larger objects, e.g. binaries. Slight increase of mapped and resident memory. Tune your system with memory options to erl for best performance.

Own Id: OTP-10840

Updated config.sub and config.guess to latest version from gnu.org

Own Id: OTP-10848

Add an xcomp file for Blue Gene/Q. Thanks to Kostis Sagonas.

Own Id: OTP-10849

Cleanup of documentation of the type language. Thanks to Kostis Sagonas.

Own Id: OTP-10850

Change the return value of hipe_bifs:remove_refs_from/1. Thanks to Kostis Sagonas.

Own Id: OTP-10851

As of ERTS-5.10/OTP-R16A node names passed in the EPMD protocol are required to be encoded in UTF-8. Since EPMD previously accepted latin1 encoded node names this is an incompatibility. However, since Erlang nodes always have required characters in node names to be 7-bit ASCII characters (and still do require this), this incompatibility should not effect anyone using EPMD as an Erlang Port Mapper Daemon.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10872 Aux Id: OTP-10753

The +pc flag to erl can be used to set the range of characters considered printable. This affects how the shell and io:format("~tp",...) functionality does heuristic string detection. More can be read in STDLIB users guide.

Own Id: OTP-10884

Fix a number of type cast errors related to formatted printing on Win64 that can potentially cause problem when the Erlang VM exceeds 4 GB of ram. (Thanks to Blaine Whittle for the original patch)

Own Id: OTP-10887

The effect of the deprecated environment variable ERL_MAX_PORTS had been removed premeturely. It has now been readded. Note that this is still scheduled to be released in R17B.

Own Id: OTP-10895

## Erts 5.10

### Fixed Bugs and Malfunctions

Set new peeled off SCTP socket to nonblocking socket (Thanks to Jonas Falkevik)

Own Id: OTP-10491

Fix various typos (thanks to Tuncer Ayaz)

Own Id: OTP-10611

Fix fd leak when using async thread pool

When using the async thread pool, if an erlang process asks to open a file and it gets shutdown/killed while the file:open/2 call hasn't returned, it's possible to leak a file descriptor against the target file. This has now been fixed. (Thanks to Filipe David Manana)

Own Id: OTP-10677

Use sys/types.h instead of string.h to pull ssize_t definition to erl_driver.h. This fixes build issue on NetBSD. (Thanks to Yamamoto Takashi).

Own Id: OTP-10699

Arguments given with the -run or -s flags to erl are now translated according to the file name encoding mode of the runtime system.

Own Id: OTP-10702

The octet counters in the gen_tcp/inet interface could behave in unexpected ways on 64bit platforms. The behaviour is now as expected.

Own Id: OTP-10746

Certain linux kernels, most notably in redhat and CentOS distribution, had a bug in writev which generated an infinite loop in the tcp code of the VM. The bug is now worked around.

Own Id: OTP-10747

A process that got killed (got an exit signal) while operating on a compresseed file, could cause a segmentation fault in the VM. This is now corrected. Thanks to Filipe David Manana for identifying the problem and submitting a solution.

Own Id: OTP-10748

Windows previously used three digit exponent in formatting which caused difference between platforms, as can be seen by float_to_list/1. This has now been fixed.

Own Id: OTP-10751

### Improvements and New Features

A boolean socket option 'ipv6_v6only' for IPv6 sockets has been added. The default value of the option is OS dependent, so applications aiming to be portable should consider using {ipv6_v6only,true} when creating an inet6 listening/destination socket, and if necessary also create an inet socket on the same port for IPv4 traffic. See the documentation.

Own Id: OTP-8928 Aux Id: kunagi-193 [104]

It is now allowed to define stubs for BIFs, to allow type specs to be written for BIFs. For example, if there is BIF called lists:member/2, a dummy definition of lists:member/2 is now allowed.

Own Id: OTP-9861

Process optimizations. The most notable:

New internal process table implementation allowing for both parallel reads as well as writes. Especially read operations have become really cheap. This reduce contention in various situations. For example when, spawning processes, terminating processes, sending messages, etc. Optimizations of run queue management reducing contention. Optimizations of process internal state changes reducing contention.

These changes imply changes of the characteristics the system. Most notable: changed timing in the system.

Own Id: OTP-9892 Aux Id: OTP-10167

Non-blocking code loading. Earlier when an Erlang module was loaded, all other execution in the VM were halted while the load operation was carried out in single threaded mode. Now modules are loaded without blocking the VM. Processes may continue executing undisturbed in parallel during the entire load operation. The load operation is completed by making the loaded code visible to all processes in a consistent way with one single atomic instruction. Non-blocking code loading will improve realtime characteristics when modules are loaded/upgraded on a running SMP system.

Own Id: OTP-9974

In the SMP emulator, turning on and off tracing will no longer take down the system to single-scheduling.

Own Id: OTP-10122

Remove VxWorks support

Own Id: OTP-10146

Added a general framework for executing benchmarks of Erlang/OTP. Benchmarks for the Erlang VM and mnesia have been incorporated in the framework.

For details about how to add more benchmarks see $ERL_TOP/HOWTO/BENCHMARKS.md in the source distribution.

Own Id: OTP-10156

Optimized deletion of ETS-tables which significantly improves performance when large amounts of temporary tables are used.

This change imply changes of the characteristics the system. Most notable: changed timing in the system.

Own Id: OTP-10167 Aux Id: OTP-9892

Tuple funs (deprecated in R15B) are no longer supported.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10170

New internal header scheme for allocators

Impact: Reduces size on object allocated in multiblock carriers by one word

Own Id: OTP-10273 Aux Id: kunagi-20 [20]

Major port improvements. The most notable:

New internal port table implementation allowing for both parallel reads as well as writes. Especially read operations have become really cheap.This reduce contention in various situations. For example when, creating ports, terminating ports, etc. Dynamic allocation of port structures. This allow for a much larger maximum amount of ports allowed as a default. The previous default of 1024 has been raised to 65536. Maximum amount of ports can be set using the +Q command line flag of erl(1). The previously used environment variable ERL_MAX_PORTS has been deprecated and scheduled for removal in OTP-R17. Major rewrite of scheduling of port tasks. Major benefits of the rewrite are reduced contention on run queue locks, and reduced amount of memory allocation operations needed. The rewrite was also necessary in order to make it possible to schedule signals from processes to ports. Improved internal thread progress functionality for easy management of unmanaged threads. This improvement was necessary for the rewrite of the port task scheduling. Rewrite of all process to port signal implementations in order to make it possible to schedule those operations. All port operations can now be scheduled which allows for reduced lock contention on the port lock as well as truly asynchronous communication with ports. Optimized lookup of port handles from drivers. Optimized driver lookup when creating ports. Preemptable erlang:ports/0 BIF. Improving responsiveness by bumping reductions for a process calling a driver callback directly.

These changes imply changes of the characteristics of the system. The most notable:

Order of signal delivery The previous implementation of the VM has delivered signals from processes to ports in a synchronous stricter fashion than required by the language. As of ERTS version 5.10, signals are truly asynchronously delivered. The order of signal delivery still adheres to the requirements of the language, but only to the requirements. That is, some signal sequences that previously always were delivered in one specific order may now from time to time be delivered in different orders. This may cause Erlang programs that have made false assumptions about signal delivery order to fail even though they previously succeeded. For more information about signal ordering guarantees, see the chapter on communication in the ERTS user's guide. The +n command line flag of erl(1) can be helpful when trying to find signaling order bugs in Erlang code that have been exposed by these changes. Latency of signals sent from processes to ports Signals from processes to ports where previously always delivered immediately. This kept latency for such communication to a minimum, but it could cause lock contention which was very expensive for the system as a whole. In order to keep this latency low also in the future, most signals from processes to ports are by default still delivered immediately as long as no conflicts occur. Such conflicts include not being able to acquire the port lock, but also include other conflicts. When a conflict occur, the signal will be scheduled for delivery at a later time. A scheduled signal delivery may cause a higher latency for this specific communication, but improves the overall performance of the system since it reduce lock contention between schedulers. The default behavior of only scheduling delivery of these signals on conflict can be changed by passing the +spp command line flag to erl(1). The behavior can also be changed on port basis using the parallelism option of the open_port/2 BIF. Execution time of the erlang:ports/0 BIF Since erlang:ports/0 now can be preempted, the responsiveness of the system as a whole has been improved. A call to erlang:ports/0 may, however, take a much longer time to complete than before. How much longer time heavily depends on the system load. Reduction cost of calling driver callbacks Calling a driver callback is quite costly. This was previously not reflected in reduction cost at all. Since the reduction cost now has increased, a process performing lots of direct driver calls will be scheduled out more frequently than before.

Potential incompatibilities:

driver_send_term() has been deprecated and has been scheduled for removal in OTP-R17. Replace usage of driver_send_term() with usage of erl_drv_send_term(). driver_output_term() has been deprecated and has been scheduled for removal in OTP-R17. Replace usage of driver_output_term() with usage of erl_drv_output_term(). The new function erl_drv_busy_msgq_limits() has been added in order to able to control management of port queues.

The driver API version has been bumped to 2.1 from 2.0 due to the above changes in the driver API.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10336 Aux Id: OTP-9892

The experimental support for packages has been removed.

Own Id: OTP-10348 Aux Id: kunagi-316 [227]

Wrong parameters when setting seq_trace-tokens from within a trace-pattern could crash the VM. This is now corrected.

Own Id: OTP-10522

Erlang specification 4.7.3 defines max tuple size to 65535 elements It is now enforced to no more than 16777215 elements (arity 24 bits)

Previous edge cases (28 bits) were not validated and could cause undefined behaviour.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10633

Add insert_element/3 and delete_element/2

Own Id: OTP-10643

The previous default of a maximum of 32768 simultaneous processes has been raised to 262144. This value can be changed using the the +P command line flag of erl(1). Note that the value passed now is considered as a hint, and that actual value chosen in most cases will be a power of two.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10647 Aux Id: OTP-9892, OTP-10336

The previously (in R15) proposed scheduler wakeup strategy is now used by default. This strategy is not as quick to forget about previous overload as the previous strategy.

This change imply changes of the characteristics the system. Most notable: When a small overload comes and then disappears repeatedly, the system will for a bit longer time be willing to wake up schedulers than before. Timing in the system will due to this also change.

The previous strategy can still be enabled by passing the +sws legacy command line flag to erl.

Own Id: OTP-10661 Aux Id: OTP-10033

The +stbt command line argument of erl was added. This argument can be used for trying to set scheduler bind type. Upon failure unbound schedulers will be used.

Own Id: OTP-10668

Support ANSI in console

Unix platforms will no longer filter control sequences to the ttsl driver thus enabling ANSI and colors in console. (Thanks to Pedram Nimreezi)

Own Id: OTP-10678

Add file:allocate/3 operation

This operation allows pre-allocation of space for files. It succeeds only on systems that support such operation. (Thanks to Filipe David Manana)

Own Id: OTP-10680

Treat -Wreturn-type warnings as error when using GCC (Thanks to Tuncer Ayaz)

Own Id: OTP-10683

Implement ./otp_build configure --enable-silent-rules

With silent rules, the output of make is less verbose and compilation warnings are easier to spot. Silent rules are disabled by default and can be disabled or enabled at will by make V=0 and make V=1. (Thanks to Anthony Ramine)

Own Id: OTP-10726

Use share flags for all file operations on Windows. Thanks to Filipe David Borba Manana.

Own Id: OTP-10727

Make/fakefop adjustments. Thanks to Tuncer Ayaz and Sebastian Rasmussen.

Own Id: OTP-10733

The runtime system will now by default use 10 async threads if thread support has been enabled when building the runtime system.

This will prevent long blocking file-operations from blocking scheduler threads for long periods of time, which can be harmful. Apart from file-operations, it also effects other operations scheduled on the async thread pool by user implemented drivers.

The amount of async threads can be controlled by using the +A command line argument of erl(1). When running some offline tools you might want to disable async threads, but you are advised not to in the general case. Instead, you might want to increase the amount of async threads used.

This change imply changes of the characteristics the system compared to the previous default. The responsiveness of the system as a whole will be improved. Operations scheduled on the async thread pool will get an increased latency. The throughput of these operations may increase, or decrease depending on the type of the operations and how they get scheduled. In the case of file operations, the throughput very much depends on how the Erlang application access files. Multiple concurrent accesses to different files have the potential of an increased throughput.

Own Id: OTP-10736

The default reader group limit has been increased to 64 from 8. This limit can be set using the +rg command line argument of erl(1).

This change of default value will reduce lock contention on ETS tables using the read_concurrency option at the expense of memory consumption when the amount of schedulers and logical processors are between 8 and 64. For more information, see documentation of the +rg command line argument of erl(1).

Own Id: OTP-10737

New BIF float_to_list/2 which solves a problem of float_to_list/1 that doesn't allow specifying the number of digits after the decimal point when formatting floats (Thanks to Serge Aleynikov).

Own Id: OTP-10752

Limited support for unicode atoms in the external format and in the internal representation of the vm. This is a preparative feature in order to support communication with future releases of Erlang/OTP that may create unicode atoms.

Own Id: OTP-10753

Increased potential concurrency in ETS for write_concurrency option. The number of internal table locks has increased from 16 to 64. This makes it four times less likely that two concurrent processes writing to the same table would collide and thereby serialized. The cost is an increased constant memory footprint for tables using write_concurrency. The memory consumption per inserted record is not affected. The increased footprint can be particularly large if write_concurrency is combined with read_concurrency.

Own Id: OTP-10787

## Erts 5.9.3.1

### Known Bugs and Problems

Create an erl_crash.dump if no heart exists and no ERL_CRASH_DUMP_SECONDS is set (behaviour changed).

Don't create an erl_crash.dump if heart do exists and no ERL_CRASH_DUMP_SECONDS is set (behaviour not changed).

This changes the behaviour back to the R15B02 default considering if a beam was running with no heart.

Own Id: OTP-10602

## Erts 5.9.3

### Fixed Bugs and Malfunctions

Fix linking in OpenBSD. (Thanks to Matthew Dempsky)

Own Id: OTP-10395

Fix bug causing fallback atomics to be used even though healthy gcc atomics or libatomic_ops was detected.

Own Id: OTP-10418

Ensure 'erl_crash.dump' when asked for it. This will change erl_crash.dump behaviour.

* Not setting ERL_CRASH_DUMP_SECONDS will now terminate beam immediately on a crash without writing a crash dump file.

* Setting ERL_CRASH_DUMP_SECONDS to 0 will also terminate beam immediately on a crash without writing a crash dump file, i.e. same as not setting ERL_CRASH_DUMP_SECONDS environment variable.

* Setting ERL_CRASH_DUMP_SECONDS to a negative value will let the beam wait indefinitely on the crash dump file being written.

* Setting ERL_CRASH_DUMP_SECONDS to a positive value will let the beam wait that many seconds on the crash dump file being written.

A positive value will set an alarm/timeout for restart both in beam and in heart if heart is running.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10422 Aux Id: kunagi-250 [161]

Fix bug where MSVRT100.dll was not included in the windows installer.

Own Id: OTP-10481

In the expression <<Bin/binary,...>>, if Bin was a bitstring with a size not a multiple of 8, either no exception was generated or an incorrect exception was generated. (Thanks to Adam Rutkowski for reporting this bug.)

Own Id: OTP-10524

The runtime system could crash while scheduling a port task. The port task was scheduled either due to an external I/O event being triggered, a driver timeout being triggered, or data being sent over a distribution channel.

Own Id: OTP-10556

erlang:memory(ets) erroneously included the size of each ETS-table main structure twice.

Own Id: OTP-10558

Fix compile error in generated file hipe_amd64_bifs.S for Solaris.

Own Id: OTP-10577

A faulty spec for process_info/2 could cause false dialyzer warnings. The spec is corrected.

Own Id: OTP-10584

In very rare cases, the VM could crash if a garbage collector was called while executing an appending bit syntax instruction. The symptom was a core when reallocating memory in the function erts_bs_append. The garbage collector bug is now corrected.

Own Id: OTP-10590

### Improvements and New Features

Improve support for building and testing in embedded ppc environments.

Own Id: OTP-10265 Aux Id: kunagi-159 [daf97f67-5724-4812-a5b6-7e86990133d2-1]

Due to a race condition on Windows, sometimes when printing to standard output and then immediately terminating erlang all data would not be printed. The emulator now waits for all data to be printed before exiting.

Own Id: OTP-10325 Aux Id: kunagi-166 [dd72d0e2-3e76-4a51-8b56-7564e24eecae]

The frequency with which sleeping schedulers are woken due to outstanding memory deallocation jobs has been reduced.

Own Id: OTP-10476 Aux Id: OTP-10162

Clearer warnings about the dangers of misuse of native functions and drivers have been added to the documentation.

Own Id: OTP-10557

## Erts 5.9.2

### Fixed Bugs and Malfunctions

Fix erl_prim_loader errors in handling of primary archive. The following errors have been corrected:

If primary archive was named "xxx", then a file in the same directory named "xxxyyy" would be interpreted as a file named "yyy" inside the archive. erl_prim_loader did not correctly create and normalize absolute paths for primary archive and files inside it, so unless given with exact same path files inside the archive would not be found. E.g. if escript was started as /full/path/to/xxx then "./xxx/file" would not be found since erl_prim_loader would try to match /full/path/to/xxx with /full/path/to/./xxx. Same problem with ../. Depending on how the primary archive was built, erl_prim_loader:list_dir/1 would sometimes return an empty string inside the file list. This was a virtual element representing the top directory of the archive. This has been removed.

Thanks to Tuncer Ayaz and Shunichi Shinohara for reporting and co-authoring corrections.

Own Id: OTP-10071

Fix: Add port-I/O statistics for active once and true and not only active false.

Own Id: OTP-10073

The 64-bit windows installer did not look in the right directories for 64-bit version of Microsoft Visual C++ 2010 Redistibutable Package and hence took the wrong decision about having to install the redistributable package if the 32-bit version was installed but not the 64-bit and vice versa. This bug has now been fixed Furthermore the sub-installer for the redistributable package is now run in silent mode if the erlang installer is.

Own Id: OTP-10096

epmd would fail to start automatically when starting a distributed erlang node installed in a location with a whitespace in the path.

Own Id: OTP-10106

A more or less harmless bug that sometimes caused memory deallocations to be delayed longer than intended has been fixed.

Own Id: OTP-10116

Fix bug causing emulator crash when running HiPE on ARM. Bug has existed since R15B.

Own Id: OTP-10137

A bug regarding spaces in C function prototypes has been fixed. (Thanks to Richard O'Keefe.)

Own Id: OTP-10138

Corrected dtrace pid length in message related probes. (Thanks to Zheng Siyao)

Own Id: OTP-10142

Correct formating in exit error messages

Ensure displayed sizes are not negative. (Thanks to Michael Santos)

Own Id: OTP-10148

fix escript/primary archive reloading

If the mtime of an escript/primary archive file changes after being added to the code path, correctly reload the archive and update the cache. (Thanks to Tuncer Ayaz)

Own Id: OTP-10151

Doc fix: link from erlang:now/0 to os:timestamp/0

Sometimes os:timestamp/0 is more appropriate than erlang:now/0. The documentation for the former has a link to the latter; this patch adds a link in the other direction to make os:timestamp/0 more visible. Thanks to Magnus Henoch

Own Id: OTP-10180

The caret in the werl window (on Windows) could appear at the wrong place after regaining focus. This is now corrected.

Own Id: OTP-10181

Fix bug that in some cases could cause corrupted binaries in ETS tables with compressed option.

Own Id: OTP-10182

Fix use of "clever" mktime

Commit 1eef765 introduced regression (conditional _always_ evaluates to true) in which erlang:localtime_to_universaltime/2 stopped working on systems configured with timezone without DST (i.e. UTC) on *BSD platforms: 1> erlang:localtime_to_universaltime({{2012,1,1},{0,0,0}}, true). ** exception error: bad argument Thanks to Piotr Sikora

Own Id: OTP-10187

Relocate bodies of DTrace probes to the statically-linked VM.

Due to various operating systems (in both the DTrace and SystemTap worlds) not fully supporting DTrace probes (or SystemTap-compatibility mode probes) in shared libraries, we relocate those probes to the statically-linked virtual machine. This could be seen as pollution of the pristine VM by a (yet) experimental feature. However:

1. This code can be eliminated completely by the C preprocessor. 2. Leaving the probes in the dyntrace NIF shared library simply does not work correctly on too many platforms. *Many* thanks to Macneil Shonle at Basho for assisting when my RSI-injured fingers gave out. (note: Solaris 10 and FreeBSD 9.0-RELEASE can take a long time to compile)

Own Id: OTP-10189

Fix bug in ets:test_ms/2 that could cause emulator crash when using '$_' in match spec.

Own Id: OTP-10190

Supplying a filename longer than the operating system MAX_PATH to file:read_link/1 would cause a crash (Segemntation fault/Critical Error) on all platforms. This is now corrected.

Own Id: OTP-10200

If Perl was configured to interpret files as being encoded in UTF-8, the build would crash in make_preload. (Thanks to Aaron Harnly for noticing this issue.)

Own Id: OTP-10201

Fix the erlc -MP flag

Because of a copy-and-paste error in erlc.c, the -MP flag had the same effect as -MG. As a workaround, you had to pass +makedep_phony to enable the MP option. This patch makes -MP work as intended.

Own Id: OTP-10211

Allow mixed IPv4 and IPv6 addresses to sctp_bindx

Also allow mixed address families to bind, since the first address on a multihomed sctp socket must be bound with bind, while the rest are to be bound using sctp_bindx. At least Linux supports adding address of mixing families. Make inet_set_faddress function available also when HAVE_SCTP is not defined, since we use it to find an address for bind to be able to mix ipv4 and ipv6 addresses. Thanks to Tomas Abrahamsson

Own Id: OTP-10217

Fix support for leap seconds-aware timezones

erlang:universaltime_to_localtime is leap seconds-aware (since 2008), however erlang:localtime_to_universaltime is not, which gives surprising results on systems configured with leap seconds-aware timezones: 1> erlang:universaltime_to_localtime({{2012,1,1},{0,0,0}}). {{2012,1,1},{0,0,0}} 2> erlang:localtime_to_universaltime({{2012,1,1},{0,0,0}}). {{2012,1,1},{0,0,24}} and completely breaks calendar:local_time_to_universal_time_dst: 3> calendar:local_time_to_universal_time_dst({{2011,1,1},{0,0,0}}). [] Thanks to Piotr Sikora

Own Id: OTP-10227

erlsrv: gracefully stop emulator on Windows shutdown

Windows will send the SERVICE_CONTROL_SHUTDOWN event to the service control handler when shutting down the system. Instead of ignoring the event, erlsrv will now invoke the stop action. Likewise, the Erlang emulator (and it's po drivers) must not quit upon reception of the CTRL_SHUTDOWN_EVENT event in th console control handler. Thanks to Jan Kloetzke

Own Id: OTP-10228

Fix dtrace bug in file rename operation.

Own Id: OTP-10234

Fix bug in memory management of driver port data locks (PDL). In some cases PDLs could be deallocated before ready_async or async_free callback was called.

Own Id: OTP-10249

### Improvements and New Features

Add port and suspend options to lock-counter profiling. (Thanks to Rick Reed)

Own Id: OTP-10051

Latency when using the active_once option in gen_tcp communication is reduced.

Own Id: OTP-10055 Aux Id: sto139

Remove bit8 option support from inet

Own Id: OTP-10056

The OS Pid of a port program is now available by calling erlang:port_info(Port,os_pid), Thanks to Matthias Lang for the original patch.

Own Id: OTP-10057

Fix openpty usage in run_erl.

Reopening a slave file descriptor which was closed earlier could lead to a misbehaving connection. This has now been remedied.

Own Id: OTP-10076

Remove all code, documentation, options and diagnostic functions which were related to the experimental hybrid heap implementation.

Own Id: OTP-10105

Optimizations of memory deallocations.

Own Id: OTP-10162 Aux Id: OTP-7775

Optimization of process locking.

Own Id: OTP-10163

Added a xcomp example file for powerpc-dso-linux-gnu

Own Id: OTP-10198

Detect when middle endian doubles are used by a platform and account for it when decoding floats. (Thanks to Mike Sperber)

Own Id: OTP-10209

## Erts 5.9.1.2

### Fixed Bugs and Malfunctions

On Linux systems using heart (erl -heart) and a HEAR_BEAT_TIMEOUT less than default, heart could fire even though Erlang was running fine after approx 298 to 497 days (depending on kernel config). This was due to the behaviour of the times(2) system call. Usage of times(2) is now replaced with clock_gettime(2) and the CLOCK_MONOTONIC clock, resulting in a more stable solution. The Erlang VM itself has used clock_gettime(2) on linux since before R12B, so this only affects the heart program.

Own Id: OTP-10111 Aux Id: seq12075

## Erts 5.9.1.1

### Fixed Bugs and Malfunctions

If threads support for the runtime system had been disabled at compile time (--disable-threads had been passed to configure), and the +A command line argument of erl was passed when starting the runtime system, driver_system_info() erroneously claimed that the runtime system had async threads even though it had not.

Due to this bug the file driver did not split tasks into smaller chunks, but instead completed the whole task at once, i.e., the scheduler got occupied with I/O for a longer time than intended.

Own Id: OTP-10059

### Improvements and New Features

A proposal for a new scheduler wakeup strategy has been implemented. For more information see the documentation of the +sws command line argument of erl.

Own Id: OTP-10033 Aux Id: Seq12025

A switch for configuration of busy wait length for scheduler threads has been added. For more information see the documentation of the +sbwt command line argument of erl.

Own Id: OTP-10044 Aux Id: Seq11976

The extra memory barriers introduced by bug-fix OTP-9281 were unnecessarily used also on tables without the write_concurrency option enabled. This could unnecessarily degrade performance of ETS tables without write_concurrency on some hardware (e.g. PowerPC) while not effecting performance at all on other hardware (e.g. x86/x86_64).

OTP-9281 (R14B03): ETS tables using the write_concurrency option could potentially get into an internally inconsistent state.

Own Id: OTP-10048 Aux Id: OTP-9281

## Erts 5.9.1

### Fixed Bugs and Malfunctions

erlang:system_profile errorneous profiled the profiler process when observing runnable processes. This has been corrected.

Own Id: OTP-9849

Calling trace_info/2 asking for information about a function that had native could could crash the run-time system.

Own Id: OTP-9886

reduce smp locking time range in erts_garbage_collect (thanks to Jovi Zhang)

Own Id: OTP-9912

Fix typo in supervisor behaviour doc (Thanks to Ricardo Catalinas Jiménez)

Own Id: OTP-9924

Correct spelling of registered (Thanks to Richard Carlsson)

Own Id: OTP-9925

erts: Remove unused variable (Thanks to Jovi Zhang)

Own Id: OTP-9926

Fix bug in ETS with compressed option and insertion of term containing large integers (>2G) on 64-bit machines. Seen to cause emulator crash. (Thanks to Diego Llarrull for excellent bug report)

Own Id: OTP-9932

Handle Linux OS where /sys/devices/system/node is only readable by root. Fallback to /sys/devices/system/cpu for topology info.

Own Id: OTP-9978

When an escript ends now all printout to standard output and standard error gets out on the terminal. This bug has been corrected by changing the behaviour of erlang:halt/0,1, which should fix the same problem for other escript-like applications, i.e that data stored in the output port driver buffers got lost when printing on a TTY and exiting through erlang:halt/0,1.

The BIF:s erlang:halt/0,1 has gotten improved semantics and there is a new BIF erlang:halt/2 to accomplish something like the old semantics. See the documentation.

Now erlang:halt/0 and erlang:halt/1 with an integer argument will close all ports and allow all pending async threads operations to finish before exiting the emulator. Previously erlang:halt/0 and erlang:halt(0) would just wait for pending async threads operations but not close ports. And erlang:halt/1 with a non-zero integer argument would not even wait for pending async threads operations.

To roughly the old behaviour, to not wait for ports and async threads operations when you exit the emulator, you use erlang:halt/2 with an integer first argument and an option list containing {flush,false} as the second argument. Note that now is flushing not dependant of the exit code, and you cannot only flush async threads operations which we deemed as a strange behaviour anyway.

Also, erlang:halt/1,2 has gotten a new feature: If the first argument is the atom 'abort' the emulator is aborted producing a core dump, if the operating system so allows.

Own Id: OTP-9985

Added check to inet driver to avoid building on operating systems that do not yet have IPv6 compatible socket API. (Thanks to Peer Stritzinger)

Own Id: OTP-9996

Fix bug when the number of CPUs actually found is lower than the configured value. (Thanks to Benjamin Herrenschmidt)

Own Id: OTP-10004

The runtime system without SMP support and without thread support erroneously busy waited when no work was present. This bug first appeared in erts-5.9.

Own Id: OTP-10019

Various typographical errors corrected in documentation for common_test, driver, erl_driver and windows installation instructions. (Thanks to Tuncer Ayaz)

Own Id: OTP-10037

Fix memory leak caused by race on exiting process

Own Id: OTP-10041

### Improvements and New Features

Add erlang:statistics(scheduler_wall_time) to ensure correct determination of scheduler utilization. Measuring scheduler utilization is strongly preferred over CPU utilization, since CPU utilization gives very poor indications of actual scheduler/vm usage.

Own Id: OTP-9858

ERTS internal API improvements. In some cases the amount of atomic read operations needed have been reduced due to this.

Own Id: OTP-9922

The DTrace source patch from Scott Lystig Fritchie is integrated in the source tree. Using an emulator with dtrace probe is still not supported for production use, but may be a valuable debugging tool. Configure with --with-dynamic-trace=dtrace (or --with-dynamic-trace=systemtap) to create a build with dtrace probes enabled. See runtime_tools for documentation and examples.

Own Id: OTP-10017

### Known Bugs and Problems

enif_make_copy may invalidate enif_inspect_binary.

Own Id: OTP-9828

## Erts 5.9.0.1

### Fixed Bugs and Malfunctions

A feature test for the lwsync instruction performed on PowerPC hardware at runtime system startup got into an eternal loop if the instruction was not supported. This bug was introduced in erts-5.9/OTP-R15B.

Own Id: OTP-9843

I/O events could potentially be delayed for ever when enabling kernel-poll on a non-SMP runtime system executing on Solaris. When also combined with async-threads the runtime system hung before completing the boot phase. This bug was introduced in erts-5.9/OTP-R15B.

Own Id: OTP-9844

## Erts 5.9

### Fixed Bugs and Malfunctions

Honor option packet_size for http packet parsing by both TCP socket and erlang:decode_packet. This gives the ability to accept HTTP headers larger than the default setting, but also avoid DoS attacks by accepting lines only up to whatever length you wish to allow. For consistency, packet type line also honor option packet_size. (Thanks to Steve Vinoski)

Own Id: OTP-9389

A few contracts in the lists module have been corrected.

Own Id: OTP-9616

The Unicode noncharacter code points 16#FFFE and 16#FFFE were not allowed to be encoded or decoded using the unicode module or bit syntax. That was inconsistent with the other noncharacters 16#FDD0 to 16#FDEF that could be encoded/decoded. To resolve the inconsistency, 16#FFFE and 16#FFFE can now be encoded and decoded. (Thanks to Alisdair Sullivan.)

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9624

Make epp search directory of current file first when including another file This completes a partial fix in R11 that only worked for include_lib(). (Thanks to Richard Carlsson)

Own Id: OTP-9645

Fixed memory leak in enif_inspect_io_list_as_binary when applied on a process independent environment.

Own Id: OTP-9668

The number of beam catches allowed in code are no longer statically defined and will grow according to its need.

Own Id: OTP-9692

Add missing parenthesis in heart doc.

Add missing spaces in the Reference Manual distributed section.

In the HTML version of the doc those spaces are necessary to separate those words.

Own Id: OTP-9693

Fixes module erlang doc style: option description (Thanks to Ricardo Catalinas Jiménez)

Own Id: OTP-9697

Specifying a scope to binary:match/3 when using multiple searchstrings resulted in faulty return values. This is now corrected.

Own Id: OTP-9701

The runtime system crashed if more than one thread tried to exit the runtime system at the same time.

Own Id: OTP-9705

Fix documentation for erlang:process_flag/2

For the subsection about process_flag(save_calls, N) there's an unrelated paragraph about process priorities which was copied from the preceding subsection regarding process_flag(priority, Level). (Thanks to Filipe David Manana)

Own Id: OTP-9714

Calls to erlang:system_flag(schedulers_online, N) and/or erlang:system_flag(multi_scheduling, block|unblock) could cause internal data used by this functionality to get into an inconsistent state. When this happened various problems occurred. This bug was quite hard to trigger, so hopefully no-one has been effected by it.

A spinlock used by the run-queue management sometimes got heavily contended. This code has now been rewritten, and the spinlock has been removed.

Own Id: OTP-9727

Use libdlpi to get physical address (Thanks to Trond Norbye)

Own Id: OTP-9818

### Improvements and New Features

An option list argument can now be passed to file:read_file_info/2, file:read_link_info/2 and file:write_file_info/3 and set time type information in the call. Valid options are {time, local}, {time, universal} and {time, posix}. In the case of posix time no conversions are made which makes the operation a bit faster.

Own Id: OTP-7687

A number of memory allocation optimizations have been implemented. Most optimizations reduce contention caused by synchronization between threads during allocation and deallocation of memory. Most notably:

Synchronization of memory management in scheduler specific allocator instances has been rewritten to use lock-free synchronization. Synchronization of memory management in scheduler specific pre-allocators has been rewritten to use lock-free synchronization. The 'mseg_alloc' memory segment allocator now use scheduler specific instances instead of one instance. Apart from reducing contention this also ensures that memory allocators always create memory segments on the local NUMA node on a NUMA system.

Own Id: OTP-7775

The ethread atomic memory operations API used by the runtime system has been extended and improved.

The ethread library now also performs runtime tests for presence of hardware features, such as for example SSE2 instructions, instead of requiring this to be determined at compile time.

All uses of the old deprecated atomic API in the runtime system have been replaced with the use of the new atomic API. In a lot of places this change imply a relaxation of memory barriers used.

Own Id: OTP-9014

gen_sctp:open/0-2 may now return {error,eprotonosupport} if SCTP is not supported

gen_sctp:peeloff/1 has been implemented and creates a one-to-one socket which also are supported now

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9239

Sendfile has been added to the file module's API. sendfile/2 is used to read data from a file and send it to a tcp socket using a zero copying mechanism if available on that OS.

Thanks to Tuncer Ayaz and Steve Vinovski for original implementation

Own Id: OTP-9240

enif_get_reverse_list function added to nif API. This function should be used to reverse small lists which are deep within other structures making it impractical to do the reverse in Erlang.

Own Id: OTP-9392

The deprecated concat_binary/1 BIF has been removed. Use list_to_binary or iolist_to_binary/1 instead.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9421

Erlang/OTP can now be built using parallel make if you limit the number of jobs, for instance using 'make -j6' or 'make -j10'. 'make -j' does not work at the moment because of some missing dependencies.

Own Id: OTP-9451

Line number and filename information are now included in exception backtraces as a fourth element in the MFA tuple. The information will be pretty-printed by the shell and used by common_test to provide better indication of where a test case.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9468

All binary constants used to be handled as heap binaries (i.e. the entire binary would be copied when sent to another process). Binary constants larger than 64 bytes are now refc binaries (i.e. the actual data in the binary will not be copied when sent to another process).

Own Id: OTP-9486

If a float and an integer is compared, the integer is only converted to a float if the float datatype can contain it. Otherwise the float is converted to an integer.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9497

Add NIF function enif_is_number

This function allows for easily determining if a term represents or not a number (integer, float, small or big).(Thanks to Filipe David Manana)

Own Id: OTP-9629

The ERTS internal system block functionality has been replaced by new functionality for blocking the system. The old system block functionality had contention issues and complexity issues. The new functionality piggy-backs on thread progress tracking functionality needed by newly introduced lock-free synchronization in the runtime system. When the functionality for blocking the system isn't used, there is more or less no overhead at all. This since the functionality for tracking thread progress is there and needed anyway.

Own Id: OTP-9631

An ERTS internal, generic, many to one, lock-free queue for communication between threads has been introduced. The many to one scenario is very common in ERTS, so it can be used in a lot of places in the future. Currently it is used by scheduling of certain jobs, and the async thread pool, but more uses are planned for the future.

Drivers using the driver_async functionality are not automatically locked to the system anymore, and can be unloaded as any dynamically linked in driver.

Scheduling of ready async jobs is now also interleaved in between other jobs. Previously all ready async jobs were performed at once.

Own Id: OTP-9632

Tuple funs (a two-element tuple with a module name and a function) are now officially deprecated and will be removed in R16. Use 'fun M:F/A' instead. To make you aware that your system uses tuple funs, the very first time a tuple fun is applied, a warning will be sent to the error logger.

Own Id: OTP-9649

Changed the internal BIF calling convention. Will make simpler faster code and allow BIFs with an arbitrary arity.

Own Id: OTP-9662

Windows native critical sections are now used internally in the runtime system on Windows as mutex implementation. This since they perform better under extreme contention than our own implementation.

Own Id: OTP-9671

Convert some erl_nif macros into inline functions. Allow for better compile time type checking. (Thanks to Tuncer Ayaz)

Own Id: OTP-9675

The +scl command line flag has been added. It can be used for disabling compaction of scheduler load. For more information see the erl(1) documentation.

Own Id: OTP-9695

The build system has been updated so that Erlang/OTP can be built on Mac OS X Lion systems without a GCC compiler. The INSTALL guide has been updated with instructions on how to install a GCC compiler and build Erlang/OTP with it, in order to get a run-time system with better performance.

Own Id: OTP-9712

When loading a module, the system use to run on a single scheduler during the entire loading process. This has been changed to only take down the system just before inserting the loaded code into the system tables, resulting in a much shorter disruption if a module is loaded in a busy system. (Suggested by Bob Ippolito.)

Own Id: OTP-9720

Possible to run HiPE without floating point exceptions (FPE). Useful on platforms that lack reliable FPE. Slower float operations compared to HiPE with FPE.

Own Id: OTP-9724

As of ERTS version 5.9 (OTP-R15B) the runtime system will by default not bind schedulers to logical processors.

If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. In some cases this performance penalty might be severe. Due to this, we change the default so that the user must make an active decision in order to bind schedulers.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9726

The use of erlang:system_flag(scheduler_bind_type, _) and erlang:system_flag(cpu_topology, _) have been deprecated and scheduled for removal in erts-5.10/OTP-R16. For more information see the documentation of erlang:system_flag/2.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9749

An ancient workaround for a Windows bug was removed from the open_port code, open_port({spawn,...}...) is now faster. Thanks to Daniel Goertzen.

Own Id: OTP-9766

The use of deprecated 32bit time_t on 32bit Windows is removed.

Own Id: OTP-9767

The NIF reload mechanism is deprecated. Do not use it as an upgrade method for live production systems. It might be removed in future releases. It can still serve as a development feature but a warning message will be logged each time it is used.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9771

The driver interface has been changed to enable 64-bit aware drivers. Most importantly the return types for ErlDrvEntry callbacks 'call' and 'control' has ben enlarged which require drivers to be changed or they will cause emulator crashes. See Rewrites for 64-bit driver interface in the driver manual.

Due to this driver version management is now mandatory. A driver that is not written with version management or a driver that was compiled with the wrong major version will be not be loaded by the emulator.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9795

Eliminate use of deprecated regexp module

Own Id: OTP-9810

## Erts 5.8.5

### Fixed Bugs and Malfunctions

Several bugs concerning constant binary constructions such as <<0:4294967295>> have been corrected. Depending on the actual size of the binary and the type of run-time system (32-bit, halfword, 64-bit), such expression could either crash the run-time system or make the loader refuse loading of the module.

Own Id: OTP-9284

The Erlsrv utility failed to stop the erlang machine if no StopAction was defined when the service was stopped. This is now corrected.

Own Id: OTP-9344

Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. A fix for this was introduced in R14B02. This fix did, however, not solve the problem. The runtime system will now issue a warning instead of aborting.

Own Id: OTP-9373 Aux Id: OTP-9009

Replace atom in DRV macro in prim_file with string

An experimental version of Dialyzer discovered that the atom that replaced the DRV macro in prim_file ends up in calls to erlang:open_port({spawn, Driver}, Portopts) as the Driver argument. The documentation states that this call requires a string there.

This change is also consistent with the one introduced in commit 0f03b1e9d2bef3bc830c31a369261af4c5234727 by Kostis Sagonas.

Own Id: OTP-9377

Fix typos in the epmd documentation (Thanks to Holger Weiß )

Own Id: OTP-9387

Fix faulty integer terms created by NIF API from 64-bit integers on halfword emulator. (Thanks to Paolo Negri and Paul Davis)

Own Id: OTP-9394

Fix epmd crash on vxworks caused by faulty argument to select() system call.

Own Id: OTP-9427 Aux Id: seq11855

The ets:test_ms function could in rare cases truncate the error messages. This is now corrected.

Own Id: OTP-9435

Fix bug related to hibernate and HiPE (clear F_HIBERNATE_SCHED flag)

F_HIBERNATE_SCHED flag that was introduced in b7ecdcd1ae9e11b8f75e must be cleared in hipe_mode_switch as well. Otherwise, processes running HiPE code that hibernate, wake up and then trap into a BIF will not be rescheduled.(Thanks to Paul Guyot)

Own Id: OTP-9452

Fix bug in FreeBSD topology detection code (Thanks to Paul Guyot)

Own Id: OTP-9453

Fix use of logical operator && with constant operand instead of bitwise & (Thanks to Cristian Greco)

Own Id: OTP-9454

inet: error if fd does not match socket domain

If an IPv4 fd is opened as an IPv6 socket, unexpected behaviour can occur. For example, if an IPv4 UDP socket is opened and passed into Erlang as an IPv6 socket, the first 3 bytes (corresponding to 1 byte representing the protocol family, 2 bytes set to the port) are stripped from the payload. The cause of the UDP payload truncation happens in inet_drv.c:packet_inet_input when a call to inet_get_address fails silently because the family is set to PF_INET6 but the buffer len is the size of an IPv4 struct sockaddr_in.

(Thanks to Andrew Tunnell-Jones for finding the bug and the test case!)

Own Id: OTP-9455

erts: use a union to avoid strict aliasing issues

Use a union for pointer type conversion to avoid compiler warnings about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not emit the warning. erts: adapt matrix_nif to R14 erl_nif API changes (Thanks To Tuncer Ayaz)

Own Id: OTP-9487

fix 64-bit issues in the garbage collection (Thanks to Richard Carlsson)

Own Id: OTP-9488

epmd: fix compiler warnings

Suppress compiler warnings about ignored return values. (Thanks to Michael Santos )

Own Id: OTP-9500

Fix non-existing function (erlang:disconnect/1) in distributed reference manual (Thanks to Fabian Król)

Own Id: OTP-9504

Document fdatasync -lrt requirement (SunOS <= 5.10) (Thanks to Tuncer Ayaz)

Own Id: OTP-9512

Let epmd ignore empty ERL_EPMD_ADDRESS

If the environment variable ERL_EPMD_ADDRESS is set to the empty string, empd now behaves like it does by default when ERL_EPMD_ADDRESS is unset. That is, in this case, epmd now listens on all available interfaces instead of using only the loopback interface, which happened because epmd added the loopback address to the (in this case empty) list of addresses specified via ERL_EPMD_ADDRESS.

Also, epmd now ignores ERL_EPMD_ADDRESS if it contains only separator characters (comma and space).

The same applies to epmd's -address option.(Thanks to Holger Weiß)

Own Id: OTP-9525

Remove dead code in erl_compile (Thanks to Tuncer Ayaz)

Own Id: OTP-9527

Add erlang:external_size/2 BIF

This BIF's second parameter is a list of options. Currently the only allowed option is {minor_version, Version} where version is either 0 (default) or 1. (Thanks to Filipe David Manana )

Own Id: OTP-9528

Fix enif_compare on 64bits machines

In 64bits machines the Sint type has a size of 8 bytes, while on 32bits machines it has a 4 bytes size. enif_compare was ignoring this and therefore returning incorrect values when the result of the CMP function (which returns a Sint value) doesn't fit in 4 bytes. (Thanks to Filipe David Manana)

Own Id: OTP-9533

Implement or fix -Werror option

If -Werror is enabled and there are warnings no output file is written. Also make sure that error/warning reporting is consistent. (Thanks to Tuncer Ayaz)

Own Id: OTP-9536

In some rare cases we did not have a run queue when scheduling misc ops. This is now fixed.

Own Id: OTP-9537

Remove misc. compiler warnings

Own Id: OTP-9542

Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.

Own Id: OTP-9544

Erlang/OTP can now be built on MacOS X Lion.

Own Id: OTP-9547

XML files have been corrected.

Own Id: OTP-9550 Aux Id: OTP-9541

Fix potential errors inspired by running cppcheck(1) (Thanks to Christian von Roques)

Own Id: OTP-9557

When auxiliary work was enqueued on a scheduler, the wakeup of the scheduler in order to handle this work could be lost. Wakeups in order to handle ordinary work were not effected by this bug. The bug only effected runtime systems with SMP support as follows:

Deallocation of some ETS data structures could be delayed. On Linux systems not using the NPTL thread library (typically ancient systems with kernel versions prior to 2.6) and Windows systems, the {Port, {exit_status, Status}} message from a terminating port program could be delayed. That is, it only effected port programs which had been started by passing exit_status as an option to open_port/2.

Own Id: OTP-9567

Handle rare race in the crypto key server functionality

Own Id: OTP-9586

### Improvements and New Features

Types and specifications have been added.

Own Id: OTP-9356

New allocator strategy "address order first fit". May ease the emptying of memory carriers and thereby real release of memory back to the OS.

Own Id: OTP-9424

The new erlang:check_old_code/1 BIF checks whether a module has old code.

Own Id: OTP-9495

Update documentation and specifications of some of the zlib functions.

Own Id: OTP-9506

Detect the available CPUs on IRIX

Add support for querying the number of configured and online processors on SGI systems running IRIX.(Thanks to Holger Weiß)

Own Id: OTP-9531

## Erts 5.8.4

### Fixed Bugs and Malfunctions

Fix binary and iolist overflow problems. Typically problems arose in length calculation where the result would exceed (1 bsl 32 - 1).

Own Id: OTP-9118

Using the old erlang shell (i.e. erl instead on werl) on windows and doing several init:restart's would eventually hang the VM. That is no longer the case.

Own Id: OTP-9139

Removed recursive C code when printing Erlang terms to buffers, avoiding stack overflows that could cause VM to crash.

Own Id: OTP-9140

The send_timeout option in gen_tcp did not work properly in active mode or with {active,once} options. This is now corrected.

Own Id: OTP-9145

Fixed various typos across the documentation (Thanks to Tuncer Ayaz)

Own Id: OTP-9154

Remove duplicate stack entries which could occur after calling certain BIFs.

Own Id: OTP-9163

A race when starting two nodes simultaneously using run_erl has been removed.

Own Id: OTP-9164

Add documentation on .erlang processing back again (Thanks to Gabor Liptak)

Own Id: OTP-9189

Remove gratuitous paren in driver_entry(Thanks to Tuncer Ayaz)

Own Id: OTP-9192

Fix some wrong pointer dereferences (Thanks to Cristian Greco)

Own Id: OTP-9194

erts: Remove unused variables (Thanks to Tuncer Ayaz)

Own Id: OTP-9205

The documentation for init:get_args/0 has been removed. init:get_args/0 itself was deprecated in R9C and removed in R12B. (Thanks to Eric Pailleau.)

Own Id: OTP-9209

Allow user to specify the IP address epmd binds to

The IP address(es) epmd binds to can now be specified by the user, either via epmd's new "-address" option or (if that's not used) by setting the environment variable ERL_EPMD_ADDRESS. Multiple addresses may be specified using a comma-separated list. If the loopback address is not in this list, it will be added implicitly, so that the daemon can be queried by an interactive epmd process.(Thanks to Holger Weiß)

Own Id: OTP-9213

epmd: include host address in local access check

In FreeBSD jails, the source and destination address of connections to localhost are changed to be the IP address of the jail. Consider connections from the host's IP address to itself (e.g., the source and destination address match) to be local for the access control checks. (Thanks to Michal Santos and Tom at diogunix.com)

Own Id: OTP-9214

Fix list returned by net_kernel:epmd_module

Function epmd_module of net_kernel returns a list instead of an atom, when the epmd_module-flag is used. (Thanks to Markus Knofe)

Own Id: OTP-9215

Fix epmd's dbg_perror() output

The dbg_perror() function now hands the current errno value over to dbg_gen_printf(). This fixes the problem that errno had been reset to zero by the time it was used (to print the corresponding error message) in the dbg_gen_printf() function. (Thanks to Holger Weiß)

Own Id: OTP-9223

heart: remove garbage appended to heart command

heart:get_cmd/0 is documented to return an empty string if the command is cleared. get_cmd/0 returns 2 extra bytes: 1 byte for the trailing null, 1 byte from the op (the op is an unsigned char and 2 bytes are allocated for it in the returned buffer). (Thanks to Michael Santos)

Own Id: OTP-9224

file: fix hang reading compressed files

The gzio driver goes into an infinite loop when reading past the end of a compressed file. Reported-By: Alex Morarash (Thanks to Michael Santos)

Own Id: OTP-9245

Eliminate alias warnings from gcc 4.5.2

Own Id: OTP-9250

Unsigned integer may overflow in error message (Thanks to Michael Santos)

Own Id: OTP-9251

Driver names should be strings, not atoms

Own Id: OTP-9253

driver_entry: Remove gratuitous paren and fix typo (Thanks to Tuncer Ayaz)

Own Id: OTP-9254

Fix format specifiers in erl_exit messages

Fix an error message by using an unsigned integer specifier as seen in a tweet by @metabrew: #erlang VM crashed with "no next heap size found: -2090496108, offset 0", suddenly allocated all available RAM

Also correct mis-typed string formats in bif.c.(Thanks to Michael Santos)

Own Id: OTP-9262

net_drv: remove unused tcp request id inet_drv: remove gratuitous assignment (Thanks to Tuncer Ayaz)

Own Id: OTP-9263

Teach run_erl RUN_ERL_DISABLE_FLOWCNTRL for disabling flow control

Flow control can cause unwanted behaviour of the beam process, if accidentally hit Ctrl-S (instead of Ctrl-D to detach) the entire beam may be blocked.

Fix this problem by making it possible to turn off flow control by setting the environment variable RUN_ERL_DISABLE_FLOWCNTRL. (Thanks to Jonas Faklkevik)

Own Id: OTP-9270

The following bugs due to missing memory barriers have been fixed:

ETS tables using the write_concurrency option could potentially get into an internally inconsistent state.

ETS tables using the ordered_set option could potentially get into an internally inconsistent state.

A number of memory barriers have been added when building with the libatomic_ops API (i.e. when passing --with-libatomic_ops=PATH to configure) and the tilera atomics API (i.e. when building for the tilera chip). Note that these bugs were due to erroneous usage of the APIs, and not in the implementations of the APIs. When using these APIs the following bugs where present:

The BIF erlang:ports/0 could return an erroneous result.

A thread blocking other threads during code loading, or setup of tracing could potentially read invalid data.

Fixation of ETS tables could potentially get into an internally inconsistent state.

Own Id: OTP-9281

Fix halfword bug for ETS ordered_set when doing select/match with partly bound key.

Own Id: OTP-9292

Fix bug in code:is_module_native that caused crash for deleted modules.

Own Id: OTP-9298

Calling driver_async_cancel() could cause a scheduler thread to enter an eternal loop doing no useful work. (Thanks to Anders Ramsell)

Own Id: OTP-9302

### Improvements and New Features

New enif_is_exception function to allow NIFs to determine whether an ERL_NIF_TERM represents an exception. (Thanks to Steve Vinoski)

Own Id: OTP-9150

A process being garbage collected by another process could be scheduled on another scheduler. This prevented this scheduler from doing any useful work until the garbage collection was done. This either occurred due to a explicit call to the garbage_collect/1 BIF, or due to a garbage collection part of code loading. A process being garbage collected like this will now not be scheduled until the garbage collection has completed.

Own Id: OTP-9211

Remove unnecessary validation copy in prim_file:drv_command/3 (Thanks to Tony Rogvall)

Own Id: OTP-9276

Symbolic link handling on windows have been slightly updated to map error conditions more consequently and correctly read directory links created outside of the Erlang environment.

Own Id: OTP-9279

Due to standard library DLL mismatches between versions of OpenSSL and Erlang/OTP, OpenSSL is now linked statically to the crypto driver on Windows. This fixes problems starting crypto when running Erlang as a service on all Windows versions.

Own Id: OTP-9280

Halfword emulator memory handling improvements:

Much more of internal memory structures have been made able to use "high" memory and are no longer restricted to the 4Gb limit that still applies for all process heap data.

Fixed faulty values from erlang:memory() caused by 32-bit counter overflow.

New counter low in erlang:memory() that sums up all memory restricted by 4Gb limit.

Own Id: OTP-9291 Aux Id: seq11841

The value set in the undocumented and unsupported ERL_version_FLAGS (e.g. ERL_R14B03_FLAGS) environment variable can now be overridden by the command line (similar to ERL_AFLAGS).

Own Id: OTP-9297

## Erts 5.8.3.2

### Known Bugs and Problems

Fix halfword emulator bug in ets:select_delete for ordered_set that caused emulator to crash.

Own Id: OTP-9258 Aux Id: seq11836

## Erts 5.8.3.1

### Fixed Bugs and Malfunctions

Ets table type ordered_set could order large integer keys wrongly on pure 64bit platforms. This is now corrected.

Own Id: OTP-9181

The status of a process was unnecessarily set to waiting before a process was enqueued in a run queue. This bug was harmless up until OTP-R14B01. In OTP-R14B02 erlang:hibernate/3 was fixed (OTP-9125). After the introduction of OTP-9125, the previously harmless process status bug sometimes caused erroneous badarg exceptions from process_info().

OTP-9125 also introduced a thread unsafe access to the status field of a process which now also have been fixed.

*** INCOMPATIBILITY with noxs ***

Own Id: OTP-9197

## Erts 5.8.3

### Fixed Bugs and Malfunctions

The scroll wheel now scrolls the werl window on Windows.

Own Id: OTP-8985

Some malformed distribution messages could cause VM to crash, this is now corrected.

Own Id: OTP-8993

The OS function getifaddrs() can return NULL in some address fields for e.g PPP and tunnel devices which caused the emulator to segfault. This bug has now been corrected.

Own Id: OTP-8996

The expression <<A:0>> would always produce an empty binary, even if A was not an integer. Corrected to cause a badarg exception if the type of A is invalid. (Thanks to Zvi.)

Own Id: OTP-8997

A bug that potentially could cause an emulator crash when deleting an ETS-table has been fixed. A resource leak when hitting the maximum amount of ETS-tables allowed has also been fixed.

Own Id: OTP-8999

A bug in the exit/2 BIF could potentially cause an emulator crash.

Own Id: OTP-9005

Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. The runtime system will now issue a warning instead of aborting.

Own Id: OTP-9009

A bug in epmd could create strange behaviour when listen() calls failed. This is now corrected thanks to Steve Vinoski.

Own Id: OTP-9024

When setting file_info the win32_driver will now correctly set access and modified time. Previously these entities were swapped.

Own Id: OTP-9046

Setting scheduler bind type to unbound failed if binding of schedulers wasn't supported, or if CPU topology wasn't present. This even though the documentation stated that it is possible to set the bind type to unbound.

Own Id: OTP-9056 Aux Id: Seq11779

Two problems were fixed in crash dump: The time left for timers are now shown as unsigned integers and the contents of ordered_set ETS tables is no longer included.

Own Id: OTP-9057

The VM could fail to set IP_TOS and SO_PRIORITY in certain situations, either because sockets were supplied as open file descriptors, or because SO_PRIORITY by default was set higher than the user can explicitly set it to. Those situations are now handled.

Own Id: OTP-9069

Wx on MacOS X generated complains on stderr about certain cocoa functions not being called from the "Main thread". This is now corrected.

Own Id: OTP-9081

Fix a couple typos in driver_entry(3) (thanks to Tuncer Ayaz).

Own Id: OTP-9085

Mention that "-detached" implies "-noinput"

Clarify that specifying "-noinput" is unnecessary if the "-detached" flag is given. (thanks to Holger Weiß)

Own Id: OTP-9086

A potential problem (found by code inspection) when calling a fun whose code was not loaded has been fixed.

Own Id: OTP-9095

The emulator could get into a state where it didn't check for I/O.

Own Id: OTP-9105 Aux Id: Seq11798

Attempting to create binaries exceeding 2Gb (using for example term_to_binary/1) would crash the emulator with an attempt to allocate huge amounts of memory. (Thanks to Jon Meredith.)

Own Id: OTP-9117

Fix erlang:hibernate/3 on HiPE enabled emulator (Thanks to Paul Guyot)

Own Id: OTP-9125

### Improvements and New Features

From this release, the previously experimental halfword emulator is now official. It can be enabled by giving the --enable-halfword-emulator option to the configure script.

The halfword emulator is a 64-bit application, but uses halfwords (32-bit words) for all data in Erlang processes, therefore using less memory and being faster than the standard 64-bit emulator. The total size of all BEAM code and all process data for all processes is limited to 4Gb, but ETS tables and off-heap binaries are only limited by the amount of available memory.

Own Id: OTP-8941

32-bit atomic memory operations have been introduced internally in the run time system, and are now used where appropriate. There were previously only atomic memory operations of word size available. The 32-bit atomic memory operations slightly reduce memory consumption, and slightly improve performance on 64-bit runtime systems.

Own Id: OTP-8974

Performance enhancements for looking up timer-entries and removing timers from the wheel.

Own Id: OTP-8990

Write accesses to ETS tables have been optimized by reducing the amount of atomic memory operations needed during a write access.

Own Id: OTP-9000

Strange C coding in the VM made the -D_FORTIFY_SOURCE option to gcc-4.5 react badly. The code is now cleaned up so that it's accepted by gcc-4.5.

Own Id: OTP-9025

The memory footprint for loaded code has been somewhat reduced (especially in the 64-bit BEAM machine).

Own Id: OTP-9030

The maximum number of allowed arguments for an Erlang function has been lowered from 256 to 255, so that the number of arguments can now fit in a byte.

Own Id: OTP-9049

Dependency generation for Makefiles has been added to the compiler and erlc. See the manual pages for compile and erlc. (Thanks to Jean-Sebastien Pedron.)

Own Id: OTP-9065

## Erts 5.8.2

### Fixed Bugs and Malfunctions

Fix format_man_pages so it handles all man sections and remove warnings/errors in various man pages.

Own Id: OTP-8600

The configure command line argument --enable-ethread-pre-pentium4-compatibility had no effect. This option is now also automatically enabled if required on the build machine.

Own Id: OTP-8847

Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.

Own Id: OTP-8876

The HiPE run-time in the 64-bit emulator could do a 64-bit write to a 32-bit struct field. It happened to be harmless on Intel/AMD processors. Corrected. (Thanks to Mikael Pettersson.)

Own Id: OTP-8877

A bug in erl_drv_tsd_get() and enif_tsd_get() could cause an emulator crash. These functions are currently not used in OTP. That is, the crash only occur on systems with user implemented NIF libraries, or drivers that use one of these functions.

Own Id: OTP-8889

Calling erlang:system_info({cpu_topology, CpuTopologyType}) with another CpuTopologyType element than one of the documented atoms defined, detected, or used caused an emulator crash. (Thanks to Paul Guyot)

Own Id: OTP-8914

The ERTS internal rwlock implementation could get into an inconsistent state. This bug was very seldom triggered, but could be during heavy contention. The bug was introduced in R14B (erts-5.8.1).

The bug was most likely to be triggered when using the read_concurrency option on an ETS table that was frequently accessed from multiple processes doing lots of writes and reads. That is, in a situation where you typically don't want to use the read_concurrency option in the first place.

Own Id: OTP-8925 Aux Id: OTP-8544

Tracing to port could cause an emulator crash when unloading the trace driver.

Own Id: OTP-8932

Removed use of CancelIoEx on Windows that had been shown to cause problems with some drivers.

Own Id: OTP-8937

The fallback implementation used when no native atomic implementation was found did not compile. (Thanks to Patrick Baggett, and Tuncer Ayaz)

Own Id: OTP-8944

Some integer values used during load balancing could under rare circumstances wrap causing a load unbalance between schedulers.

Own Id: OTP-8950

The windows VM now correctly handles appending to large files (> 4GB).

Own Id: OTP-8958

Name resolving of IPv6 addresses has been implemented for Windows versions that support it. The use of ancient resolver flags (AI_V4MAPPED | AI_ADDRCONFIG) to the getaddrinfo() function has been removed since e.g FreeBSD regard mapped IPv4 addresses to be a security problem and the semantics of the address configured flag is uncertain.

Own Id: OTP-8969

### Improvements and New Features

The help texts produced by the configure scripts in the top directory and in the erts directory have been aligned and cleaned up.

Own Id: OTP-8859

When the runtime system had fewer schedulers than logical processors, the system could get an unnecessarily large amount reader groups.

Own Id: OTP-8861

run_rel has been updated to support Solaris's /dev/ptmx device and to load the necessary STREAMS modules so that to_erl can provide terminal echo of keyboard input. (Thanks to Ryan Tilder.)

Own Id: OTP-8878

The Erlang VM now supports Unicode filenames. The feature is turned on by default on systems where Unicode filenames are mandatory (Windows and MacOSX), but can be enabled on other systems with the '+fnu' emulator option. Enabling the Unicode filename feature on systems where it is not default is however considered experimental and not to be used for production. Together with the Unicode file name support, the concept of "raw filenames" is introduced, which means filenames provided without implicit unicode encoding translation. Raw filenames are provided as binaries, not lists. For further information, see stdlib users guide and the chapter about using Unicode in Erlang. Also see the file module manual page.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8887

Buffer overflows have been prevented in erlc, dialyzer, typer, run_test, heart, escript, and erlexec.

(Thanks to Michael Santos.)

Own Id: OTP-8892

The runtime system is now less eager to suspend processes sending messages over the distribution. The default value of the distribution buffer busy limit has also been increased from 128 KB to 1 MB. This in order to improve throughput.

Own Id: OTP-8901

The distribution buffer busy limit can now be configured at system startup. For more information see the documentation of the erl +zdbbl command line flag. (Thanks to Scott Lystig Fritchie)

Own Id: OTP-8912

The inet driver internal buffer stack implementation has been rewritten in order to reduce lock contention.

Own Id: OTP-8916

New ETS option compressed, to enable a more compact storage format at the expence of heavier table operations. For test and evaluation, erl +ec can be used to force compression on all ETS tables.

Own Id: OTP-8922 Aux Id: seq11658

There is now a new function inet:getifaddrs/0 modeled after C library function getifaddrs() on BSD and LInux that reports existing interfaces and their addresses on the host. This replaces the undocumented and unsupported inet:getiflist/0 and inet:ifget/2.

Own Id: OTP-8926

Support for detection of CPU topology and binding of schedulers on FreeBSD 8 have been added. (Thanks to Paul Guyot)

Own Id: OTP-8939

Several bugs related to hibernate/3 and HiPE have been corrected. (Thanks to Paul Guyot.)

Own Id: OTP-8952

Support for soft and hard links on Windows versions and filesystems that support them is added.

Own Id: OTP-8955

The win32 virtual machine is now linked large address aware. his allows the Erlang VM to use up to 3 gigs of address space on Windows instead of the default of 2 gigs.

Own Id: OTP-8956

## Erts 5.8.1.2

### Fixed Bugs and Malfunctions

Fix that the documentation top index generator can handle an Ericsson internal application group.

Own Id: OTP-8875

In embedded mode, on_load handlers that called code:priv_dir/1 or other functions in code would hang the system. Since the crypto application now contains an on_loader handler that calls code:priv_dir/1, including the crypto application in the boot file would prevent the system from starting.

Also extended the -init_debug option to print information about on_load handlers being run to facilitate debugging.

Own Id: OTP-8902 Aux Id: seq11703

## Erts 5.8.1.1

### Fixed Bugs and Malfunctions

Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.

Own Id: OTP-8876

## Erts 5.8.1

### Fixed Bugs and Malfunctions

Very small floating point numbers generated errors when converting from list to float in some versions of the VM, this is now corrected so that i.e. list_to_float("1.0e-324"). returns 0.0 in all versions of Erlang.

Own Id: OTP-7178

Windows Vista and Windows 7 file system virtualization, which makes "old style" windows programs execute in a file system sandbox, was previously unintentionally turned on for the Erlang VM. This is now corrected so that i.e. writes to C:\Program Files\. without administrator privileges will fail.

Own Id: OTP-7405

Fix faulty 64-bit integer term output from drivers. Large 64-bits integers did not generate correct bignums and could even cause emulator crash. Only affects drivers using ERL_DRV_INT64 or ERL_DRV_UINT64, introduced in R13B03.

Own Id: OTP-8716

Fixed: inet:setopts(S, [{linger,{true,2}}]) returned {error,einval} for SCTP sockets. The inet_drv had a bug when checking the option size.

Own Id: OTP-8726 Aux Id: seq11617

Fix libm linking with --as-needed flag

When building with "--as-needed" linker flags on Linux the build will fail. This has now been fixed.

(Thanks to Christian Faulhammer)

Own Id: OTP-8728

gen_udp:connect/3 was broken for SCTP enabled builds. It did not detect remote end errors as it should.

Own Id: OTP-8729

Reduce the risk of integer wrapping in bin vheap size counting.

The vheap size series will now use the golden ratio instead of doubling and fibonacci sequences.

Own Id: OTP-8730

ETS ordered_set containing [] as key could cause strange thing to happen, like an infinite hanging ets:select.

Own Id: OTP-8732

reference() has been substituted for ref() in the documentation.

Own Id: OTP-8733

When a native compiled module called a not loaded non-native compiled module that had an on_load function, the export entries were trashed after code loading so on the next call from the native compiled module to the non-native compiled the emulator crashed. This bug has now been fixed.

Own Id: OTP-8736

HiPE-enabled Erlang VMs running on BSD systems sometimes generated messages like "Yikes! erts_alloc() returned misaligned address 0x8016a512c". Fixed. (Thanks to Mikael Pettersson.)

Own Id: OTP-8769

A race condition in erts_poll() could cause delay of poll for I/O.

Own Id: OTP-8773

Removed some potential vulnerabilities from the Erlang Port Mapper Daemon (epmd) and straightened up access control. Also removed hazardous interfaces allowing anyone on a machine to forcefully unregister other nodes. This means that the ei_unregister/erl_unregister interfaces in erl_interface is rendered not only error prone and mystifying as before, but totally ineffective. The old behaviour of unchecked node unregistering can be restored if needed, see epmd documentation for details.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8780

Building in a source tree without prebuilt platform independent build results failed on the SSL examples when:

cross building. This has been solved by not building the SSL examples during a cross build. building on Windows.

Own Id: OTP-8791

inet:getsockopt for SCTP sctp_default_send_param had a bug to not initialize required feilds causing random answers. It is now corrected.

Own Id: OTP-8795 Aux Id: seq11655

The hipe_bifs:get_hrvtime/0 BIF now always returns a real value even if the "perfctr" Linux kernel extension is not available. It used to return a dummy value. (Thanks to Mikael Pettersson.)

Own Id: OTP-8798

Calling a native-code compiled module with an on_load function could cause a crash. (Thanks to Mikael Pettersson.)

Own Id: OTP-8799

The emulator could crash while writing a crash dump if native-compiled modules had been loaded. (Thanks to Paul Guyot.)

Own Id: OTP-8801

The garbage collector could crash if invoked from native-compiled code after a call to a BIF. (Thanks to Paul Guyot.)

Own Id: OTP-8821

A rare memory leak in binary:matches is removed

Own Id: OTP-8823

For a socket in the HTTP packet mode, the return value from gen_tcp:recv/2,3 if there is an error in the header will be {ok,{http_error,String}} instead of {error,{http_error,String}} to be consistent with ssl:recv/2,3.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8831

### Improvements and New Features

ets:select_reverse/{1,2,3} are now documented.

Own Id: OTP-7863

External format of integers changed to make full use of all 32 bits of INTEGER_EXT. This is a compatible change as old code can read full 32-bit integers but only produce 28-bit integers as INTEGER_EXT.

Own Id: OTP-8540 Aux Id: seq11534

Large parts of the ethread library have been rewritten. The ethread library is an Erlang runtime system internal, portable thread library used by the runtime system itself.

Most notable improvement is a reader optimized rwlock implementation which dramatically improve the performance of read-lock/read-unlock operations on multi processor systems by avoiding ping-ponging of the rwlock cache lines. The reader optimized rwlock implementation is used by miscellaneous rwlocks in the runtime system that are known to be read-locked frequently, and can be enabled on ETS tables by passing the {read_concurrency, true} option upon table creation. See the documentation of ets:new/2 for more information. The reader optimized rwlock implementation can be fine tuned when starting the runtime system. For more information, see the documentation of the +rg command line argument of erl.

There is also a new implementation of rwlocks that is not optimized for readers. Both implementations interleaves readers and writers during contention as opposed to, e.g., the NPTL (Linux) pthread rwlock implementation which use either a reader or writer preferred strategy. The reader/writer preferred strategy is problematic since it starves threads doing the non-preferred operation.

The new rwlock implementations in general performs better in ERTS than common pthread implementations. However, in some extremely heavily contended cases this is not the case. Such heavy contention can more or less only appear on ETS tables. This when multiple processes do very large amounts of write locked operations simultaneously on the same table. Such use of ETS is bad regardless of rwlock implementation, will never scale, and is something we strongly advise against.

The new rwlock implementations depend on atomic operations. If no native atomic implementation is found, a fallback solution will be used. Using the fallback implies a performance degradation. That is, it is more important now than before to build OTP with a native atomic implementation.

The ethread library contains native atomic implementations for, x86 (32 and 64 bit), powerpc (32 bit), sparc V9 (32 and 64 bit), and tilera (32 bit). On other hardware gcc's builtin support for atomic memory access will be used if such exists. If no such support is found, configure will warn about no atomic implementation available.

The ethread library can now also use the libatomic_ops library for atomic memory accesses. This makes it possible for the Erlang runtime system to utilize optimized native atomic operations on more platforms than before. If configure warns about no atomic implementation available, try using the libatomic_ops library. Use the --with-libatomic_ops=PATH configure command line argument when specifying where the libatomic_ops installation is located. The libatomic_ops library can be downloaded from: http://www.hpl.hp.com/research/linux/atomic_ops/

The changed API of the ethread library has also caused modifications in the Erlang runtime system. Preparations for the to come "delayed deallocation" feature has also been done since it depends on the ethread library.

Note: When building for x86, the ethread library will now use instructions that first appeared on the pentium 4 processor. If you want the runtime system to be compatible with older processors (back to 486) you need to pass the --enable-ethread-pre-pentium4-compatibility configure command line argument when configuring the system.

Own Id: OTP-8544

erlang:localtime_to_universaltime({{2008, 8, 1}, {0, 0, 0}},true) when TZ=UTC now behaves consistently on all Unix platforms.

The problem fixed was originally reported by Paul Guyot on erlang-bugs mailing list:

http://www.erlang.org/pipermail/erlang-bugs/2008-November/001077.html

Own Id: OTP-8580

Optimization reducing memory consumption by two words per ETS object.

Own Id: OTP-8737

Fixes for unsupported halfword-emulator

Own Id: OTP-8745

NIF 64-bit integer support; enif_get_int64, enif_get_uint64, enif_make_int64, enif_make_uint64.

Own Id: OTP-8746

Alignment of trailing data in messages has been adjusted. This in order to be able to pass data of any type as trailing data in the future.

Own Id: OTP-8754

The obsolete/driver.h header file has been removed. It has been obsolete and deprecated since R8B. Drivers that still include obsolete/driver.h must be updated to include erl_driver.h.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8758

Added erlang:system_info(build_type) which makes it easier to chose drivers, NIF libraries, etc based on build type of the runtime system.

The NIF library for crypto can now be built for valgrind and/or debug as separate NIF libraries that will be automatically loaded if the runtime system has been built with a matching build type.

Own Id: OTP-8760

Further lessened the memory requirements of ETS objects.

Own Id: OTP-8762

The broken elib_malloc alternate memory allocator has been removed. erlang:system_info(elib_malloc) will always return false, and in R15, erlang:system_info(elib_malloc) will fail with a badarg exception.

Own Id: OTP-8764

Calling erlang:system_info/1 with the new argument update_cpu_info will make the runtime system reread and update the internally stored CPU information. For more information see the documentation of erlang:system_info(update_cpu_info).

The CPU topology is now automatically detected on Windows systems with less than 33 logical processors. The runtime system will now, also on Windows, by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers is at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.

Own Id: OTP-8765

The SMP ERTS internal child waiter thread used on Linux system with NPTL was unintentionally disabled during cross compilation rewrites (OTP-8323 in R13B03). It has now been re-enabled. Enabling it again gives a slight performance improvement.

Own Id: OTP-8774

epmd used to generate a message to the syslog when it started up, which could be annoying. This has been changed to only generate the message if the debug swith is given. (Thanks to Michael Santos.)

Own Id: OTP-8775

The scheduler wakeup threshold is now possible to adjust at system boot. For more information see the +swt command line argument of erl.

Own Id: OTP-8811

The undocumented function inet:ifget/2 has been improved to return interface hardware address (MAC) on platforms supporting getaddrinfo() (such as BSD unixes). Note it still does not work on all platforms for example not Windows nor Solaris, so the function is still undocumented.

Buffer overflow and field init bugs for inet:ifget/2 and inet:getservbyname/2 has also been fixed.

Thanks to Michael Santos.

Own Id: OTP-8816

Optimizations for MIPS when using gcc atomics. (Thanks to Steve Vinoski)

Own Id: OTP-8834

Lock optimization in timer functionality.

Own Id: OTP-8835

### Known Bugs and Problems

Fix epmd and build environment to build on VxWorks

Own Id: OTP-8838

## Erts 5.8

### Fixed Bugs and Malfunctions

Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.

Own Id: OTP-8475

The use of mmap() was unnecessarily disabled when cross compiling.

The configure arguments --with-ssl, and --with-odbc refused to accept libraries outside of $erl_xcomp_sysroot when cross compiling for no good reason.

The configure argument --with-odbc didn't handle the value yes correct.

The configure arguments --with-odbc, and --without-odbc have also been added to the configure help.

(Thanks to Steve Vinoski for reporting these issues)

Own Id: OTP-8484

A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)

Own Id: OTP-8487

The runtime system crashed if fewer logical processors were found than reported by sysconf( SC_NPROCESSORS_CONF).

Own Id: OTP-8549

Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.

Own Id: OTP-8591 Aux Id: seq11554

Port locks could be prematurely destroyed.

Own Id: OTP-8612

The empd program could loop and consume 100% CPU time if an unexpected error occurred in listen() or accept(). Now epmd will terminate if a non-recoverable error occurs. (Thanks to Michael Santos.)

Own Id: OTP-8618

When kernel poll has been enabled, a livelock could in rare circumstances occur. Problem reported by Chetan Ahuja, fix by Mikael Pettersson.

Own Id: OTP-8632

Windows: Closing port of program that stalled without reading all data could deadlock scheduler thread.

Own Id: OTP-8641

On some combination of Montavista Linux on Cavium Octeon processors, some socket-related system calls returned other numbers than -1 for errors. This caused a core dump in inet_drv.c. Now the code works around this problem.

Own Id: OTP-8654

Missing memory barriers in erts_poll() could cause the runtime system to hang indefinitely.

Own Id: OTP-8658

ethr_rwmutex_tryrlock() acquired and refused to acquire a lock with inverted logic. The lock was however never acquired in a thread unsafe manner. (Thanks to JR Zhang for noting this issue)

Own Id: OTP-8662

Extreme combinations of register/unregister in a highly parallell SMP application could crash the VM. The error is corrected.

Own Id: OTP-8663

On Windows, files are now opened with FILE_SHARE_DELETE to get closer to Unix semantics.

Own Id: OTP-8667

erlang:system_info(multi_scheduling) sometimes erroneously returned enabled when it should have returned blocked.

Own Id: OTP-8675

Fix bug causing erlang:decode_packet and enif_make_string to generate faulty strings with negative character values for ascii values larger than 127. (Thanks to Paul Guyot)

Own Id: OTP-8685

open_port/2 with the spawn and spawn_executable options can include an {env,Env} option. In some cases unsetting variables would not work on Unix (typically if more variables were unset than were actually present in the environment).

Own Id: OTP-8701

A user defined CPU topology set via a call to erlang:system_flag(cpu_topology, CPUTopology) was not properly verified, and could in worst case cause an emulator crash. The emulator crash could only occur when a user defined CPU topology already existed and was redefined.

Own Id: OTP-8710

### Improvements and New Features

The grammar for match specifications in ERTS users guide only described the tracing dialect of match specifications. An informal grammar for the ETS dialect is added.

Own Id: OTP-8086 Aux Id: seq11333

The module binary from EEP31 (and EEP9) is implemented.

Own Id: OTP-8217

New NIF API function enif_make_new_binary

Own Id: OTP-8474

The guard BIF is_boolean/1 (introduced in R10B) has now been included in the lists of BIFs allowed in guards in the Reference Manual.

Own Id: OTP-8477

Added function zip:foldl/3 to iterate over zip archives.

Added functions to create and extract escripts. See escript:create/2 and escript:extract/2.

The undocumented function escript:foldl/3 has been removed. The same functionality can be achieved with the more flexible functions escript:extract/2 and zip:foldl/3.

Record fields has been annotated with type info. Source files as been adapted to fit within 80 chars and trailing whitespace has been removed.

Own Id: OTP-8521

A regular expression with many levels of parenthesis could cause a buffer overflow. That has been corrected. (Thanks to Michael Santos.)

Own Id: OTP-8539

erlang:decode_packet(httph_bin,..) could return corrupt header strings or even crash the VM. This has been fixed. It only happened on 32-bit VM if the header name was unknown and between 16 and 20 characters long. Sockets with simular packet option did not suffer from this bug.

Own Id: OTP-8548

New NIF features:

Send messages from a NIF, or from thread created by NIF, to any local process (enif_send) Store terms between NIF calls (enif_alloc_env, enif_make_copy) Create binary terms with user defined memory management (enif_make_resource_binary)

And some incompatible changes made to the API. For more information see the warning text in erl_nif(3).

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8555

If the 'fop' program (needed for building PDF files) cannot not be found, it is now possible to build the HTML and man pages anyway (there will also be dummy PDF files with no real content created). (Thanks to Tuncer Ayaz.)

Own Id: OTP-8559

When defining macros the closing right parenthesis before the dot is now mandatory.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8562

Local and imported functions now override the auto-imported BIFs when the names clash. The pre R14 behaviour was that auto-imported BIFs would override local functions. To avoid that old programs change behaviour, the following will generate an error:

Doing a call without explicit module name to a local function having a name clashing with the name of an auto-imported BIF that was present (and auto-imported) before OTP R14A

Explicitly importing a function having a name clashing with the name of an autoimported BIF that was present (and autoimported) before OTP R14A

Using any form of the old compiler directive nowarn_bif_clash

If the BIF was added or auto-imported in OTP R14A or later, overriding it with an import or a local function will only result in a warning,

To resolve clashes, you can either use the explicit module name erlang to call the BIF, or you can remove the auto-import of that specific BIF by using the new compiler directive -compile({no_auto_import,[F/A]})., which makes all calls to the local or imported function without explicit module name pass without warnings or errors.

The change makes it possible to add auto-imported BIFs without breaking or silently changing old code in the future. However some current code ingeniously utilizing the old behaviour or the nowarn_bif_clash compiler directive, might need changing to be accepted by the compiler.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8579

A bug in re that could cause certain regular expression matches never to terminate is corrected. (Thanks to Michael Santos and Gordon Guthrie.)

Own Id: OTP-8589

The erlang:open_port spawn and spawn_executable directives can include an {env,Env} directive to set up environment variables for the spawned process. A bug prevented applications from using {env,Env} to set an environment variable whose value ended with a '=' (equal sign) character; the trailing equal sign was mistaken as an indication that an environment variable was to be cleared from the environment of the spawned process. (Thanks to Steve Vinoski.)

Own Id: OTP-8614

receive statements that can only read out a newly created reference are now specially optimized so that it will execute in constant time regardless of the number of messages in the receive queue for the process. That optimization will benefit calls to gen_server:call(). (See gen:do_call/4 for an example of a receive statement that will be optimized.)

Own Id: OTP-8623

The functions file:advise/4 and file:datasync/1 have been added. (Thanks to Filipe David Manana.)

Own Id: OTP-8637

New NIF API functions: enif_make_atom_len, enif_make_existing_atom_len, enif_make_string_len, enif_get_atom_length, enif_get_list_length, enif_is_list, enif_is_tuple (by Tuncer Ayaz)

Own Id: OTP-8640

Support for using gcc's built-in functions for atomic memory access has been added. This functionallity will be used if available and no other native atomic implementation in ERTS is available.

Own Id: OTP-8659

The number of spinlocks used when implementing atomic fall-backs when no native atomic implementation is available has been increased from 16 to 1024.

Own Id: OTP-8660

Writer preferred pthread read/write locks has been enabled on Linux.

Own Id: OTP-8661

The runtime system will by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers are at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.

NOTE: If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. If this is the case you, are are advised to unbind the schedulers using the +sbtu command line argument, or by invoking erlang:system_flag(scheduler_bind_type, unbound).

Own Id: OTP-8666

The recently added BIFs erlang:min/2, erlang:max/2 and erlang:port_command/3 are now auto-imported (as they were originally intended to be). Due to the recent compiler change (OTP-8579), the only impact on old code defining it's own min/2, max/2 or port_command/3 functions will be a warning, the local functions will still be used. The warning can be removed by using -compile({no_auto_import,[min/2,max/2,port_command/3]}). in the source file.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8669 Aux Id: OTP-8579

There is a new option 'exclusive' to file:open/2 that uses the OS O_EXCL flag where supported to open the file in exclusive mode.

Own Id: OTP-8670

Now, binary_to_term/2 is auto-imported. This will cause a compile warning if and only if a module has got a local function with that name.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8671

Alignment of scheduler data and run queues were adjusted.

Own Id: OTP-8673

Call time breakpoint tracing

Introduce a call_time option to erlang:trace_pattern/3.This option enables call time breakpoint tracing on code that is executed by processes with call tracing enabled. Call time tracing stores the number of calls and the time spent of each function with this trace pattern enabled. The information can be retrieved with erlang:trace_info/2 Add a scheduler array for BpData. To solve the issue of multiple schedulers constantly updating the head pointer to the bp data wheel, each scheduler now has its own entrypoint to the wheel. This head pointer can be updated without a locking being taken.

Teach call count tracing to use atomics

Call count previously used a global lock for accessing and writing its counter in the breakpoint. This is now changed to atomics instead. The change will let call count tracing and cprof to scale better when increasing the number of schedulers.

Own Id: OTP-8677

eprof has been reimplemented with support in the Erlang virtual machine and is now both faster (i.e. slows down the code being measured less) and scales much better. In measurements we saw speed-ups compared to the old eprof ranging from 6 times (for sequential code that only uses one scheduler/core) up to 84 times (for parallel code that uses 8 cores).

Note: The API for the eprof has been cleaned up and extended. See the documentation.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8706

## Erts 5.7.5.2

### Known Bugs and Problems

Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.

Own Id: OTP-9544

## Erts 5.7.5.1

### Fixed Bugs and Malfunctions

Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.

Own Id: OTP-8475

A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)

Own Id: OTP-8487

Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.

Own Id: OTP-8591 Aux Id: seq11554

## Erts 5.7.5

### Fixed Bugs and Malfunctions

Fix binary_to_term crash on compressed term with corrupt size field.

Own Id: OTP-8336

Processes and/or ports could get stuck on a blocked scheduler when erlang:system_flag(multi_scheduling, block) was used.

Processes and/or ports could get stuck on an offline scheduler when schedulers online were reduced using erlang:system_flag(schedulers_online, SchedulersOnline).

Own Id: OTP-8342

Building on Windows will now work if the paths to mc.exe and rc.exe contain spaces. The README.win32 file has been updated with some information about building using Visual Studio 2008. (Thanks to Andrew Thompson.)

Own Id: OTP-8345

EPMD now correctly handles the extra data field which can be given in the ALIVE2_REQ request and retrieved in the PORT2_RESP response. (Thanks to Klas Johansson.)

Own Id: OTP-8361

The configure test for reliable floating point exceptions has been update to work on modern versions of Mac OS X. (Thanks to Trannie Carter.)

Own Id: OTP-8368

ERTS makefiles used to detect the use of a gcc C compiler by checking if CC equaled gcc. That is, the makefiles failed to detect gcc C compilers with other command line names than gcc. `configure' now substitute GCC into the makefiles. If CC is a gcc C compiler, GCC will have the value yes. (Thanks to Jean-Sébastien Pédron)

Own Id: OTP-8373

ETS bug causing the memory counter from ets:info for ordered_set's to sometimes get out of synch and absurdly high.

Own Id: OTP-8377 Aux Id: seq11442

Immediately repeated multi-scheduling block/unblock cycles using erlang:system_flag(multi_scheduling, block | unblock) could deadlock the runtime system.

Own Id: OTP-8386

A number of bugs concerning re and unicode are corrected:

re:compile no longer loses unicode option, which also fixes bug in re:split.

re:replace now handles unicode charlist replacement argument

re:replace now handles unicode RE charlist argument correctly

re:replace now handles binary unicode output correctly when nothing is replaced.

Most code, testcases and error isolation done by Rory Byrne.

Own Id: OTP-8394

The loading of native code was not properly atomic in the SMP emulator, which could cause crashes. Also a per-MFA information table for the native code has now been protected with a lock since it turns that it could be accessed concurrently in the SMP emulator. (Thanks to Mikael Pettersson.)

Own Id: OTP-8397

Fix processes in exiting status that are about to be scheduled, to not be allowed to garbage collect.

Own Id: OTP-8420

Removed bogus "\011" character sequence in documentation.

Own Id: OTP-8422

The resolver routines failed to look up the own node name as hostname, if the OS native resolver was erroneously configured, bug reported by Yogish Baliga, now fixed.

The resolver routines now tries to parse the hostname as an IP string as most OS resolvers do, unless the native resolver is used.

The DNS resolver inet_res and file resolver inet_hosts now do not read OS configuration files until they are needed. Since the native resolver is default, in most cases they are never needed.

The DNS resolver's automatic updating of OS configuration file data (/etc/resolv.conf) now uses the 'domain' keyword as default search domain if there is no 'search' keyword.

Own Id: OTP-8426 Aux Id: OTP-8381

The re module: A regular expression with an option change at the start of a pattern that had top-level alternatives could cause overwriting and/or a crash. (Thanks to Michael Santos.)

Own Id: OTP-8438

Harmless buffer overflow by one byte in asn1 and ram_file_drv.

Own Id: OTP-8451

### Improvements and New Features

Improved GC performance after BIF/NIF call when a lot of heap fragments was created. This will mainly benefit NIFs that return large compound terms.

Own Id: OTP-8240

Incompatible changes in the experimental NIF feature.

Changed the NIF function prototypes in order to allow more than 3 function arguments. enif_get_data renamed as enif_priv_data. enif_make_string got a third argument for character encoding. The return value of erlang:load_nif/2 on error changed.

Read more in the documentation of erl_nif and erlang:load_nif/2

.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8304

Cross compilation improvements and other build system improvements.

Most notable:

Lots of cross compilation improvements. The old cross compilation support was more or less non-existing as well as broken. Please, note that the cross compilation support should still be considered as experimental. Also note that old cross compilation configurations cannot be used without modifications. For more information on cross compiling Erlang/OTP see the $ERL_TOP/INSTALL-CROSS.md file. Support for staged install using DESTDIR. The old broken INSTALL_PREFIX has also been fixed. For more information see the $ERL_TOP/INSTALL.md file. Documentation of the release target of the top Makefile. For more information see the $ERL_TOP/INSTALL.md file. make install now by default creates relative symbolic links instead of absolute ones. For more information see the $ERL_TOP/INSTALL.md file. $ERL_TOP/configure --help=recursive now works and prints help for all applications with configure scripts. Doing make install, or make release directly after make all no longer triggers miscellaneous rebuilds. Existing bootstrap system is now used when doing make install, or make release without a preceding make all. The crypto and ssl applications use the same runtime library path when dynamically linking against libssl.so and libcrypto.so. The runtime library search path has also been extended. The configure scripts of Erl_interface and ODBC now search for thread libraries and thread library quirks the same way as ERTS do. The configure script of the odbc application now also looks for odbc libraries in lib64 and lib/64 directories when building on a 64-bit system. The config.h.in file in the erl_interface application is now automatically generated in instead of statically updated which reduces the risk of configure tests without any effect.

(Thanks to Henrik Riomar for suggestions and testing)

(Thanks to Winston Smith for the AVR32-Linux cross configuration and testing)

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-8323

NIF improvements:

Driver API for multi-threading made available for NIFs. Support for mempory managed (garbage collected) resource objects. A way to pass "pointers" to native data structures between C and Erlang in a safe way. Support for references, floats and term comparison. Various new functions, like enif_inspect_iolist_as_binary, enif_make_sub_binary, enif_get_string, enif_get_atom, enif_make_tuple_from_array, enif_make_list_from_array, enif_make_existing_atom.

Own Id: OTP-8335

Minor alignment adjustments of scheduler specific data.

Own Id: OTP-8341

The documentation is now possible to build in an open source environment after a number of bugs are fixed and some features are added in the documentation build process.

- The arity calculation is updated.

- The module prefix used in the function names for bif's are removed in the generated links so the links will look like "http://www.erlang.org/doc/man/erlang.html#append_element-2" instead of "http://www.erlang.org/doc/man/erlang.html#erlang:append_element-2".

- Enhanced the menu positioning in the html documentation when a new page is loaded.

- A number of corrections in the generation of man pages (thanks to Sergei Golovan)

- The legal notice is taken from the xml book file so OTP's build process can be used for non OTP applications.

Own Id: OTP-8343

There is new erlang:binary_to_term/2 BIF that takes an option list. The option safe can be used to prevent creation of resources that are not garbage collected (such as atoms). (Thanks to Jayson Vantuyl.)

Own Id: OTP-8367

The default settings for garbage collection of binaries has been adjusted to be less aggressive than in R13B03. It is now also possible configure the settings for binary GC. See the documentation for spawn_opt/2-5, erlang:system_info/1, erlang:system_flag/2, process_flag/2-3, erlang:trace/3, and the documenation for erl for the new command line options +hms and +hmbs.

Own Id: OTP-8370

A bug causing memory corruption in re:run() has been corrected. (Thanks to Yamashina Hio.)

Own Id: OTP-8375

The -Werror option for erlc and the compiler option warnings_as_errors will cause warnings to be treated as errors. (Thanks to Christopher Faulet.)

Own Id: OTP-8382

Explicit top directories in archive files are now optional.

For example, if an archive (app-vsn.ez) just contains an app-vsn/ebin/mod.beam file, the file info for the app-vsn and app-vsn/ebin directories are faked using the file info from the archive file as origin. The virtual direcories can also be listed. For short, the top directories are virtual if they does not exist.

Own Id: OTP-8387

An unnecessary lock operation in os:timestamp/0 has been eliminated, making it slightly more efficient. (Thanks to Jonas Falkevik and Tuncer Ayaz.)

Own Id: OTP-8390

There is a new +t emulator option for changing the maximum number of atoms. (Thanks to Julien Barbot.)

Own Id: OTP-8405

Fixed numerous compiler warnings generated by gcc 4.4.1 and tile-cc 2.0.1.78377 when compiling the runtime system.

Own Id: OTP-8412

configure learned the option --enable-m32-build to force the building of a 32-bit run-time on systems where the default C compiler generates 64-bit executables by default.

Own Id: OTP-8415

HiPE now works in the 64-bit emulator on Mac OS X. (Thanks to Geoff Cant.)

Own Id: OTP-8416

Improved handling of symbolic links to escripts

Own Id: OTP-8417

Add lock profiling tool.

The Lock profiling tool, lcnt, can make use of the internal lock statistics when the runtime system is built with this feature enabled.

This provides a mechanism to examine potential lock bottlenecks within the runtime itself.

- Add erts_debug:lock_counters({copy_save, bool()}). This option enables or disables statistics saving for destroyed processes and ets-tables. Enabling this might consume a lot of memory.

- Add id-numbering for lock classes which is otherwise undefined.

Own Id: OTP-8424

Removed spurious options to the emulator from escript.

Own Id: OTP-8427

Minor documentation fixes. Mainly anchor adjustments.

Own Id: OTP-8457

## Erts 5.7.4

### Fixed Bugs and Malfunctions

An insufficient stack allocation was made when reading CPU information on BSD operating systems. (Thanks Michael Turner and Akira Kitada)

Own Id: OTP-8207

A bug when supplying an argument without a dash directly after the program name when starting erlang could prevent distribution to start. This is now corrected.

Own Id: OTP-8209

A ticker process could potentially be blocked indefinitely trying to send a tick to a node not responding. If this happened, the connection would not be brought down as it should.

Own Id: OTP-8218

Using certain firewalls (i.e. MS IAS Client and certain versions of COMODO) could expose an undocumented behaviour in the Win32 socket interface causing the name resolution calls to hang infinitely. This is now worked around by adding possibilities for port programs under Windows to use overlapped I/O on their standard input/output file handles.

Own Id: OTP-8230

Fixed bug on ETS tables with write_concurrency. The emulator could crash when doing a select or match with a bound key without finding any object.

Own Id: OTP-8242

The information-request / information-response, and group-leader-change-request / group-leader-changed-response signal pairs described below did not always adhere to the signal order guarantees of Erlang's signal model in the runtime system with SMP support. These signals could for example sometimes pass exit signals.

The following BIFs behaviors can be modeled as if an asynchronous information-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous information-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF.

is_process_alive(Pid) erlang:process_display(Pid, Type) process_info(Pid) process_info(Pid, ItemSpec)

When Pid resides on the same node as the caller of group_leader(GroupLeader, Pid), the group_leader/2 BIFs behavior can be modeled as if an asynchronous group-leader-change-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous group-leader-changed-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF. The distributed case which only consists of an asynchronous group-leader-change-request signal and no response is not effected.

Own Id: OTP-8245

Errors in the system_profile documentation has been corrected.

Own Id: OTP-8257

Low watermark socket option modified high watermark instead of low watermark in the inet_driver. (Thanks to Feng Yu and Tuncer Ayaz)

Own Id: OTP-8279

A race condition could cause the runtime system with SMP support to end up in a completely unresponsive state.

Own Id: OTP-8297

### Improvements and New Features

The use of pthread_cond_timedwait() have been completely removed from the runtime system. This since its behavior is unpredictable when the system clock is suddenly changed. The previous use of it was harmless.

Own Id: OTP-8193

The documentation is now built with open source tools (xsltproc and fop) that exists on most platforms. One visible change is that the frames are removed.

Own Id: OTP-8201

A new garbage collecting strategy for binaries which is more aggressive than the previous implementation. Binaries now has a virtual binary heap tied to each process. When binaries are created or received to a process it will check if the heap limit has been reached and if a reclaim should be done. This imitates the behavior of ordinary Erlang terms. The virtual heaps are grown and shrunk like ordinary heaps. This will lessen the memory footprint of binaries in a system.

Own Id: OTP-8202

The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_INT64, and ERL_DRV_UINT64 for passing 64-bit integers. Also the 64-bit integer data types ErlDrvSInt64 and ErlDrvUInt64 have been introduced.

For more information see the erl_driver(3) documentation.

Own Id: OTP-8205

[escript] The restriction that the first line in escripts must begin with #! has been removed.

[escript] Some command line options to the escript executable has now been documented. For example you can run an escript in the debugger by just adding a command line option.

[escript] The documentation of the escript header syntax has been clarified. For example the header is optional. This means that it is possible to directly "execute" .erl, .beam and.zip files.

Own Id: OTP-8215

The instruction for building OTP on Windows was outdated and incomplete, the document is updated.

Also the otp_build script required windows drives to show up in Cygwin using the /cygdrive prefix. That requirement is now removed.

Own Id: OTP-8219

A module can have native implemented functions (NIFs) that are dynamically loaded by calling erlang:load_nif/2. This is an experimental feature that is not yet intended for production systems. It is released with intention to get some early feedback on the interfaces before they are carved in stone.

Own Id: OTP-8220

The float/1 BIF would always force a garbage collection. The BIFs size/1, byte_size/1, bit_size/1, abs/1, and round/1 would force a garbage-collection if the result was not a sufficiently small integer.

Own Id: OTP-8221

The erlang:port_command/3 BIF has been added. erlang:port_command/3 is currently not auto imported, but it is planned to be auto imported in OTP R14. For more information see the erlang(3) documentation.

Own Id: OTP-8225

'configure --enable-darwin-64bit' would fail if Snow Leopard had been booted with the 64-bit kernel. (Thanks to Ryan M. Graham.)

Own Id: OTP-8236

## Erts 5.7.3

### Fixed Bugs and Malfunctions

On Windows, open_port({spawn,Command},Opts) could not run executables with spaces in the path or filename, regardless of quoting efforts. While open_port({spawn_executable,Exec},Opts) can run any executable, it was still impossible to use 'spawn' to do the same thing. This is now corrected.

Own Id: OTP-8055

The scheduler bind type processor_spread spread schedulers too much on large NUMA systems.

The new scheduler bind type spread spreads schedulers as much as possible, and behaves as processor_spread previously did. For more information see the documentation of the +sbt command line argument in the erl(1) documentation, and the documentation of erlang:system_flag(scheduler_bind_type, SchedulerBindType).

Own Id: OTP-8063

Automatically detected CPU topology on Linux system could erroneously contain logical processors with -1 as identifiers. This happened when sysconf(_SC_NPROCESSORS_CONF) returned a value larger than the amount of logical processors found.

Own Id: OTP-8064

When the minimal term [] (end of list) was sent as the complete message to a process on another node, and received there, it could not be decoded. This bug is now corrected. Fortunately [] is uncommon as the complete message in real applications but it is a serious bug anyway.

Own Id: OTP-8092

A bug when the floating point exception pointer was not initialized has been corrected. It manifested itself on CentOS 5.1 sometimes when a floating point value was sent to a remote node. Bug reported and patch suggested by David Reiss, confirmed by Mikael Pettersson.

Some build problems on IRIX was also corrected. Problem reported by Patrick Baggett, patch by Mikael Pettersson.

Own Id: OTP-8095

A terminating process could erroneously unregister a name for another process. This could occur under the following conditions: The name of the terminating process was unregistered and then registered for another process simultaneously as the process that first had the name was terminating.

Own Id: OTP-8099 Aux Id: seq11344

Running erlc in a very deep directory (with a path length of more 256 or more characters) would cause the emulator to crash in a call to list_to_atom/1. (Thanks to Chris Newcombe.)

Own Id: OTP-8124

A deadlock of the runtime system could occur when unregistering the name of a port.

Own Id: OTP-8145

Makefile.in has been updated to use the LDFLAGS environment variable (if set). (Thanks to Davide Pesavento.)

Own Id: OTP-8157

The pthread rwlock implemention on Linux could cause starvation of writers. We, therefore, now use our own rwlock implementation on Linux.

Own Id: OTP-8158

Open source Erlang builds are updated to work well on Snow Leopard (MacOS X 10.6)

Own Id: OTP-8168

A call to erlang:system_info(schedulers_online) could end up in an infinite loop. This happened if the amount of schedulers was larger than one, the amount of schedulers online was one, and someone was blocking multi-scheduling.

Own Id: OTP-8169

An error in erlang:system_profile/2 could cause timestamped messages to arrive out of order in the SMP case. This has now been fixed.

Own Id: OTP-8171

binary_to_atom/2 and binary_to_existing_atom/2 would leak memory if the binary contained unaligned data.

Own Id: OTP-8192

The async thread pool in the runtime system without SMP support used a memory allocator that was not thread safe for async jobs.

Own Id: OTP-8194

### Improvements and New Features

Processor internal NUMA nodes are now supported in the ERTS internal CPU topology representation. For more information see the documentation of the +sct command line argument in the erl(1) documentation, and the documentation of erlang:system_info(cpu_topology).

Own Id: OTP-8041

Documentation for ets improved about concurrency.

Own Id: OTP-8050

Emulator flags in an escript were earlier inherited to emulators started from from the emulator running the escript. For example when an escript invoked os:cmd("erl"), the new emulator were given erroneous emulator flags. This bug has now been fixed

Escript filenames may now contain dots.

Own Id: OTP-8060

Made some BIFs non-recursive (relational operators,hash and phash) to limit internal stack usage.

Own Id: OTP-8065

Fixed Windows specific bug in erl_prim_loader. Now it handles the root directory (e.g. c:/) better. This bug affected the directory listing in the debugger.

Own Id: OTP-8080

A TCP socket with option {packet,4} could crash the emulator if it received a packet header with a very large size value (>2Gb). The same bug caused erlang:decode_packet/3 to return faulty values. (Thanks to Georgos Seganos.)

Own Id: OTP-8102

The maximum size of the export table has been raised from 65536 to 524288 entries.

Own Id: OTP-8104 Aux Id: seq11345

The file module has now a read_line/1 function similar to the io:get_line/2, but with byte oriented semantics. The function file:read_line/1 works for raw files as well, but for good performance it is recommended to use it together with the 'read_ahead' option for raw file access.

Own Id: OTP-8108

Fixed bug causing emulator crash when reading a term in external format containing a corrupt list with a negative length.

Own Id: OTP-8117

New emulator flag +sss, to set stack size of scheduler threads.

Own Id: OTP-8119

The Windows utility Erlsrv, run in interactive mode now accepts options for registering internal service name and description field of Windows registry database.

Own Id: OTP-8132

erlang:demonitor(Mon, [flush]) has been optimized. Previously it always searched the message queue of the caller for a 'DOWN' message. Current implementation only search the message queue when necessary. It is quite common that the search is not necessary.

A new option info has been added to erlang:demonitor/2. For more information see the erlang(3) documentation.

Own Id: OTP-8143

I/O tasks could unnecessarily be rescheduled. This was harmless, but not useful work.

Own Id: OTP-8148

Minor improvements of erlang:memory/[1,2].

Own Id: OTP-8152

New configuration option to enable use of shared zlib.

Own Id: OTP-8155

Fixed smp bug in ETS that could cause emulator crash when table with more than 1000 objects accessed by several processes, including calls to variants of select or match combined with concurrent object deletion.

Own Id: OTP-8166 Aux Id: seq11392

The code path interpretation is now more relaxed. The flag -code_path_choice now defaults to relaxed instead of strict. See the documentation of code and init for more info.

Own Id: OTP-8170

Load balancing of run queues and check for I/O are triggered more often than before in situations where processes are scheduled often but are doing very little work each time they execute.

Own Id: OTP-8172

Call tracing binary comprehensions would cause an emulator crash. (Thanks to Paul Mineiro.)

Own Id: OTP-8179

binary_to_term/1 would crash the emulator instead of generating a badarg exception when given certain invalid terms. (Thanks to Scott Lystig Fritchie.)

Own Id: OTP-8180

## Erts 5.7.2

### Fixed Bugs and Malfunctions

Crash dumps should now cause less problems for the crashdump_viewer application. (For processes where arity was non-zero, the arguments are now longer printed - they used to be printed in a format that was not parseable.)

Own Id: OTP-7472 Aux Id: seq11019, 11292

Processes could potentially get stuck on an offline scheduler.

Own Id: OTP-7990

binary_to_atom/2 and binary_to_existing_atom/2 could leak memory if they caused a badarg exception.

Own Id: OTP-7997

A process could under very rare circumstances erroneously be resumed.

Own Id: OTP-8000

Load balancing between schedulers could under rare circumstances cause an emulator crash.

Own Id: OTP-8008

erlang:memory(processes_used) always returned 0 instead of the correct value. (Thanks to Geoff Cant)

Own Id: OTP-8022

### Improvements and New Features

Major improvements of the Erlang distribution for Erlang runtime systems with SMP support. Previously distribution port locks were heavily contended, and all encoding and decoding for a specific distribution channel had to be done in sequence. Lock contention due to the distribution is now negligible and both encoding and decoding of Erlang messages can be done in parallel.

The old atom cache protocol used by the Erlang distribution has been dropped since it effectively prevented all parallel encoding and decoding of messages passed over the same distribution channel.

A new atom cache protocol has been introduced which isolates atom cache accesses and makes parallel encoding and decoding of messages passed over the same distribution channel possible. The new atom cache protocol also use an atom cache size 8 times larger than before. The new atom cache protocol is documented in the ERTS users guide.

Erlang messages received via the distribution are now decoded by the receiving Erlang processes without holding any distribution channel specific locks. Erlang messages and signals sent over the distribution are as before encoded by the sending Erlang process, but now without holding any distribution channel specific locks during the encoding. That is, both encoding and decoding can be and are done in parallel regardless of distribution channel used.

The part that cannot be parallelized is the atom cache updates. Atom cache updates are therefore now scheduled on the distribution port. Since it is only one entity per distribution channel doing this work there is no lock contention due to the atom cache updates.

The new runtime system does not understand the old atom cache protocol. New and old runtime systems can however still communicate, but no atom cache will be used.

Own Id: OTP-7774

Fixed a bug that caused error logging from driver_select sometimes with additional symptoms such as failing IP communications or even an emulator crash.

Own Id: OTP-7898 Aux Id: seq11304

Improved SMP concurrency for ETS tables. Several mutating operations can now be performed truly concurrent on different records of the same table. To support this, the table has to be created with option write_concurrency, as it is achieved at the expense of some execution and memory overhead. ets:select and select_count has also been improved for all tables to not acquire exclusive table lock during the iteration.

Own Id: OTP-7922

erl (that is erl.exe and dyn_erl) and erlexec has been made more dynamic so no hard coded paths needs to added at installation time to erl (that is erl.ini and erl). Reltool will make use of this in a future release.

Own Id: OTP-7952

Added functionality to get higher resolution timestamp from system. The erlang:now function returns a timestamp that's not always consistent with the actual operating system time (due to resilience against large time changes in the operating system). The function os:timestamp/0 is added to get a similar timestamp as the one being returned by erlang:now, but untouched by Erlangs time correcting and smoothing algorithms. The timestamp returned by os:timestamp is always consistent with the operating systems view of time, like the calendar functions for getting wall clock time, but with higher resolution. Example of usage can be found in the os manual page.

Own Id: OTP-7971

Two new options are added to open_port - spawn_executable which runs external executables in a controlled way, and spawn_driver which only opens port to loaded Erlang drivers. See the erlang manual page for details.

Own Id: OTP-7995

New functionality in ETS to transfer the ownership of a table. A table can either change owner be declaring an "heir", another process that will inherit the table if the owner terminates. A table can also change owner by calling a new function ets:give_away.

Own Id: OTP-8006

Updates to Tilera build environment.

Own Id: OTP-8009

A stack trace was unnecessarily saved during process termination.

Own Id: OTP-8014

User defined CPU topology and scheduler bind type can now be set from the command line when starting an emulator. For more information see the documentation of the +sct, and the +sbt emulator flags in the erl(1) documentation.

The CPU topologies returned from erlang:system_info/1 and erlang:system_flag/2 now always contain the processor level, also when not strictly necessary.

Own Id: OTP-8030

Various fixes in ETS: ets:first could return a deleted key in a fixated table. ets:lookup could return objects out of order if a deleted object was re-inserted into a fixed bag. ets:delete_object could fail to delete duplicate objects in a duplicate_bag.

Own Id: OTP-8040

## Erts 5.7.1

### Fixed Bugs and Malfunctions

Fixed a bug on Windows that could make gen_tcp:send hang trying to send an iolist of more than 16 binaries.

Own Id: OTP-7816

The runtime system could under rare circumstances crash during load balancing.

Own Id: OTP-7908 Aux Id: otp-7500

run_erl uses fallback if Unix98 pseudo-terminal is not present on host.

Own Id: OTP-7916 Aux Id: seq11249

A message buffer memory leak in the runtime system without smp support has been fixed.

Own Id: OTP-7941

Attempting to append a binary of 16Mb or greater to another binary using the bit syntax would cause a system_limit exception. There was also several cases when constructing binaries when a badarg exception was generated when it should have been system_limit.

Own Id: OTP-7942

The runtime system with SMP support failed to terminate the caller of link(RemotePid) properly, if RemotePid was the pid of a process on an unreachable node. The calling process was in this case marked as exiting, but never terminated.

Own Id: OTP-7946

### Improvements and New Features

Rudimentary support for cross compiling is added to the source release. The support is still in its infancy and has only been used to cross compile on Linux for a different cpu architecture and a different Linux version, but should be extendible to support other platforms as well. The cross configuration files with examples are placed in $ERL_TOP/xcomp/. View README.xcomp and run $ERL_TOP/otp_build -help for further information.

Own Id: OTP-7854

The escape sequence \{ which was given a new interpretation in R13A has retained its old meaning (the ASCII code for {), which means that codes greater than 255 have to be stated using hexadecimal characters (for example, \x{AAA}). The escape sequence \xH where H is a hexadecimal character followed by something else but a hexadecimal character is no longer valid (incompatibility with R13A). Character codes less than 256 can be stated using two hexadecimal characters (for example, \x0D).

Own Id: OTP-7891 Aux Id: OTP-7855

The term_to_binary/1 BIF used to be implemented with recursive C code, which could cause the Erlang emulator to terminate because of a stack overflow.

Also fixed some minor issues in term_to_binary/1 and binary_to_term/1 pointed out by Matthew Dempsky.

Own Id: OTP-7894

Several glitches and performance issues in the Unicode and I/O-system implementation of R13A have been corrected.

Own Id: OTP-7896 Aux Id: OTP-7648 OTP-7887

Minor documentation improvements of the scheduler_bind_type argument of erlang:system_flag/2, and the scheduler_bind_type, and the scheduler_bindings arguments of erlang:system_info/1.

Own Id: OTP-7901 Aux Id: OTP-7777

There is a new BIF erlang:make_tuple/3.

Own Id: OTP-7913

## Erts 5.7

### Fixed Bugs and Malfunctions

OpenSource:

FreeBSD leap-seconds are handled according to patch submitted by OpenSource user Kenji Rikitake. No test case covers this functionality (unsupported platform).

Own Id: OTP-7609

A corrected bug in ETS for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.

Own Id: OTP-7665

A new driver call-back stop_select is introduced to allow drivers to de-select and then close a file descriptor in a safe way in a SMP emulator. The old way was not strictly according to posix standard and could in some rare cases lead to unexpected behavior. A new flag ERL_DRV_USE can be passed to driver_select() to tell it that the descriptor should be closed. stop_select is then called when it is safe to do so. Old drivers will however still work as before.

Own Id: OTP-7670

A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.

Own Id: OTP-7682 Aux Id: OTP-7647

run_erl did in some cases fail to extract control sequences from to_erl (like: winsize=X,Y) and did instead send them to be interpreted by the erlang shell.

Own Id: OTP-7688

A bug in the installer on Windows not updating file associations properly is now corrected.

Own Id: OTP-7746

More space than necessary could be allocated in binaries when appending to a binary (also in a binary comprehension) and the data appended did not consist of wholes bytes (e.g. 13 bits).

Own Id: OTP-7747

The gen_sctp option sctp_peer_addr_params, #sctp_paddrparams{address={IP,Port} was erroneously decoded in the inet driver. This bug has now been corrected.

Own Id: OTP-7755

Outstanding async driver jobs leaked memory if the issuing port died before the async jobs completed.

Own Id: OTP-7784

A bug in the dynamic library loading affecting, among others, OpenSolaris is now corrected. (Thanks to Paul Fisher.)

Own Id: OTP-7796

run_erl compile errors fixed for FreeBSD

Own Id: OTP-7817

A bug in the inet driver for SCTP on Solaris showing for e.g gen_sctp:abort/1 and gen_sctp:eof/1 has been corrected. Patch suggestion by Simon Cornish.

Own Id: OTP-7866

### Improvements and New Features

The order of objects visited in select for ordered_set is now documented.

Own Id: OTP-7339

The runtime system with SMP support now uses multiple, scheduler specific run queues, instead of one globally shared run queue.

The lock protecting the shared run queue was heavily contended, and the shared run queue also caused Erlang processes to randomly migrate between schedulers with negative cache effects as a result.

With the current scheduler specific run queue solution, lock contention due to run queue protection has been reduced, and Erlang processes are only migrated when needed to balance the load between the schedulers. The reduced amount of migration also reduce lock contention on locks protecting the scheduler specific instances of the erts internal memory allocators.

The scheduler specific run queues are also a necessity for a lot of future planned NUMA (Non-Uniform Memory Access) specific optimizations.

Own Id: OTP-7500

Support for Unicode is implemented as described in EEP10. Formatting and reading of unicode data both from terminals and files is supported by the io and io_lib modules. Files can be opened in modes with automatic translation to and from different unicode formats. The module 'unicode' contains functions for conversion between external and internal unicode formats and the re module has support for unicode data. There is also language syntax for specifying string and character data beyond the ISO-latin-1 range.

The interactive shell will support input and output of unicode characters when the terminal and operating system supports it.

Please see the EEP and the io/io_lib manual pages as well as the stdlib users guide for details.

I/O-protocol incompatibilities:

The io_protocol between io_Server and client is updated to handle protocol data in unicode formats. The updated protocol is now documented. The specification resides in the stdlib users manual, which is a new part of the manual.

io module incompatibilities:

The io:put_chars, io:get_chars and io:get_line all handle and return unicode data. In the case where binaries can be provided (as to io:put_chars), they shall be encoded in UTF-8. When binaries are returned (as by io:get_line/get_chars when the io_server is set in binary mode) the returned data is also always encoded as UTF-8. The file module however still returns byte-oriented data, why file:read can be used instead of io:get_chars to read binary data in ISO-latin-1.

io_lib module incompatibilities:

io_lib:format can, given new format directives (i.e "~ts" and "~tc"), return lists containing integers larger than 255.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7648 Aux Id: OTP-7580 OTP-7514 OTP-7494 OTP-7443 OTP-7181 EEP10 EEP11

The format of the string returned by erlang:system_info(system_version) (as well as the first message when Erlang is started) has changed. The string now contains the both the OTP version number as well as the erts version number.

Own Id: OTP-7649

Message passing has been further optimized for parallel execution. Serial message passing is slightly more expensive than before, but parallel send to a common receiver is much cheaper.

Own Id: OTP-7659

Lock contention on the atom table lock when decoding Erlang terms on the external format has been drastically reduced.

Own Id: OTP-7660

The undocumented, unsupported, and deprecated guard BIF is_constant/1 has been removed.

*** INCOMPATIBILITY with R12B ***

Own Id: OTP-7673

The Erlang process lock implementation has been improved by Mat Hostetter at Tilera Corporation.

Own Id: OTP-7692

A {nodedown, Node} message passed by the net_kernel:monitor_nodes/X functionality is now guaranteed to be sent after Node has been removed from the result returned by erlang:nodes/Y.

Own Id: OTP-7725

The short-circuit operators andalso and orelse no longer guarantees that their second argument is either true or false. As a consequence, andalso/orelse are now tail-recursive.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7748

A new BIF, lists:keyfind/3, has been added. It works like lists:keysearch/3 except that it does not wrap the returned tuple in a value tuple in case of success. (Thanks to James Hague for suggesting this function.)

Own Id: OTP-7752

Optimization for drivers by creating small binaries direct on process heap.

Own Id: OTP-7762

I bsl N could cause the Erlang virtual machine to run of memory instead generating a system_limit if N was absurdly huge. (Thanks to Daniel Hedlund.)

There would always be a garbage collection when evaluating I bsl N or I bsr N if I was a bignum.

If I is an integer and N a bignum, I bsl N will now cause the correct system_limit exception instead of bad_arith as in earlier releases.

If I is an integer and N a bignum, I bsr N will return either 0 or -1 depending on the sign of I instead of causing a bad_arith exception as in earlier releases.

Own Id: OTP-7764

Scheduler threads can now be bound to logical processors on newer Linux and Solaris systems. More systems will be supported in the future.

In some cases performance has increased drastically when binding schedulers. Schedulers are not bound by default, though. This since it might cause a performance degradation if multiple programs have bound to processors, e.g. multiple Erlang runtime systems. For more information see the documentation of erlang:system_flag/2.

In order to bind scheduler threads the CPU topology need to be known. On some newer Linux and Solaris systems the runtime system automatically detects the CPU topology. If the emulator isn't able to automatically detect the CPU topology, the CPU topology can be defined. For more information see the documentation of erlang:system_flag/2.

Own Id: OTP-7777

The compiler will refuse to a compile file where the module name in the file differs from the output file name.

When compiling using erlc, the current working directory will no be included in the code path (unless explicitly added using "-pa .").

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7793

The BIFs atom_to_binary/2, binary_to_atom/2, and binary_to_existing_atom/2 have been added.

Own Id: OTP-7804

The amount of schedulers online can now be changed during operation. The amount of schedulers online defaults to the same amount as available logical processors. For more information see the documentation of erlang:system_flag/2 and erl.

Own Id: OTP-7811

The deprecated functions erlang:fault/1, erlang:fault/2, and file:rawopen/2 have been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7812

Erts internal dynamically allocated process and port specific data for rarely used data. This is used to reduce memory usage of processes and ports that do not use specific functionality. More functionality will be moved to process and port specific data in future releases.

Own Id: OTP-7818

New packet type http_bin for gen_tcp sockets and erlang:decode_packet. It works like http except that strings are returned as binaries instead of lists.

Own Id: OTP-7821

The obsolete wd_keeper program for embedded Solaris systems has been removed.

Own Id: OTP-7822

Nodes belonging to different independent clusters can now co-exist on the same host with the help of a new environment variable setting ERL_EPMD_PORT.

Own Id: OTP-7826

There are new functions erlang:min/2 and erlang:max/2 to calculate the minimum and maximum of two terms, respectively. Note that the functions are not auto-imported, so they need to be imported explicitly or the erlang prefix must be used when calling them.

Own Id: OTP-7841

The copyright notices have been updated.

Own Id: OTP-7851

Enhanced build environment for cross compilation to Tilera Tile architecture.

Support for native ethread atomics on Tilera Tile64/TilePro (Thanks to Tilera Corporation).

Own Id: OTP-7852

The escape sequences \x and \{ have been assigned new interpretations (they used to return the ASCII code for x and { respectively). One or more octal characters inside curly brackets after a leading backslash is from now on an alternative to the existing syntax \NNN, but can also be used for codes greater than 255. In a similar fashion, one or more hexadecimal characters can be put inside curly brackets after a leading \x. Furthermore, the escape sequences \xH and \xHH, where N is a hexadecimal character, can be used for codes less than 256.

NOTE: These new escape sequences are still considered experimental and may be changed in the R13B release.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7855

The PCRE library's exported function names are now prefixed with erts_ in the erlang emulator to avoid clashes with dynamically loaded drivers.

Own Id: OTP-7861

A runtime system with SMP support will now be built by default on most platforms if a usable posix thread library or native windows threads are found.

For more information see the top README file.

Own Id: OTP-7872

## Erts 5.6.5.1

### Fixed Bugs and Malfunctions

A corrected bug in ETS for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.

Own Id: OTP-7665

A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.

Own Id: OTP-7682 Aux Id: OTP-7647

Calling gen_tcp:send() from several processes on socket with option send_timeout could lead to much longer timeout than specified. The solution is a new socket option {send_timeout_close,true} that will do automatic close on timeout. Subsequent calls to send will then immediately fail due to the closed connection.

Own Id: OTP-7731 Aux Id: seq11161

A process being garbage collected via the garbage_collect/1 BIF or the check_process_code/2 BIF didn't handle message receive and resume correctly during the garbage collect. When this occurred, the process returned to the state it had before the garbage collect instead of entering the new state.

Own Id: OTP-7738

## Erts 5.6.5

### Fixed Bugs and Malfunctions

A bug in inet_drv concerning gen_tcp:connect has been corrected. A connect towards a non-open port through open firewalls could sometimes erroneously be successful. Any subsequent operation would fail, though.

Own Id: OTP-6542

Floating point arithmetics in drivers could cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

Own Id: OTP-7237

A bug when many sockets got signalled simultaneously causing the emulator to panic with the message "Inconsistent, why isnt io reported?" is now corrected.

Own Id: OTP-7420

Starting erl with option "-detached" now disconnects correctly from terminal session on Unix.

Own Id: OTP-7461

Mended gdb etp-commands for ETS access.

Own Id: OTP-7538

erlang:decode_packet/3 allows white space between HTTP header tag and colon according to RFC2616.

Own Id: OTP-7543

An emulator compiled for SCTP now starts even if the dynamic libraries are not present. The SCTP driver is then of course not loaded.

Own Id: OTP-7551

To build on Mac OS X, 10.3.0 or later is now required because of fixes for two problems:

There would be a resource leak when erl_ddl attempted to unload a driver. This problem has been corrected by using dlopen() (which works on all modern Unix-like platforms) instead of the Mac OS X specific API calls.

Signal handling in the run-time system for HiPE has been updated to work on later versions of Mac OS X than 10.2.x. Therefore, --enable-hipe now works on Mac OS X with Intel CPUs.

Thanks to Geoff Cant for the patches.

Own Id: OTP-7562

Corrected some information about the protocol between EPMD and Erlang nodes. (Thanks to Michael Regen.)

Own Id: OTP-7594

When using erlang:system_monitor(Pid,{long_gc,Time}), and the GC time exceeded 1 second, it sometimes erroneously showed up as about 4300 seconds. (This bug was corrected in R9C, but re-introduced in R12B.) (Thanks to Chris Newcombe.)

Own Id: OTP-7622 Aux Id: OTP-4903, seq8379

### Improvements and New Features

The driver entry of a dynamically loaded driver is now copied when loaded which enables some internal optimizations. Note that drivers that modify the driver entry during execution will not work anymore. Such a miss-use of the driver interface is however not supported.

Own Id: OTP-6900

The split function is now added to the re library. Exceptions and errors from both run, replace and split are made more consistent.

Own Id: OTP-7514 Aux Id: OTP-7494

Fixed harmless compiler warnings when building the emulator and minor build changes in order to avoid unnecessary rebuilds.

Own Id: OTP-7530

There is now experimental support for loading of code from archive files. See the documentation of code, init, erl_prim_loader and escript for more info.

The error handling of escripts has been improved.

An escript may now set explicit arguments to the emulator, such as -smp enabled.

An escript may now contain a precompiled beam file.

An escript may now contain an archive file containing one or more applications (experimental).

The internal module code_aux has been removed.

Own Id: OTP-7548 Aux Id: otp-6622

The reallocation functionality part of the ERTS internal memory allocators, now consider current block in combination with surrounding free blocks as an alternative location for a reallocation.

Own Id: OTP-7555

There could remain false references from a process to a module that has been called earlier, so that the process would be killed if the module was reloaded. (Thanks to Richard Carlsson.)

Also, the fix for this bug also made it possible to make stack backtraces (as returned from erlang:get_stacktrace/0 and other functions) more correct in that the immediate caller is always included in the stack backtrace (it could sometimes be missing).

Own Id: OTP-7559

Improved locking in IO-handling for better smp performance.

Own Id: OTP-7560

Improved BIF rescheduling functionality.

Own Id: OTP-7587

Loading a module compiled with Erlang/OTP R9C and calling module_info/0 in the module would crash the emulator. The emulator now refuses to load any module compiled with R9C or earlier. (Note: only trivial modules compiled with R10B or earlier could be loaded anyway.) (Thanks to Martin Kjellin.)

Own Id: OTP-7590

## Erts 5.6.4.2

### Fixed Bugs and Malfunctions

A process calling one of the following BIFs could under very rare conditions deadlock in the runtime system with SMP support: check_process_code/2, garbage_collect/1, process_info/[1,2], system_flag/2, and erlang:suspend_process/[1,2].

Own Id: OTP-7582

A couple of statistics variables were not managed in a thread safe manner in the runtime system with SMP support.

Own Id: OTP-7583

An extremely rare race condition when terminating a process could potentially cause a runtime system crash.

Own Id: OTP-7584

Under certain conditions and when using run_erl/to_erl, the terminal Erlang driver (ttsl_drv) could crash the emulator by doing a division by zero due to incorrect handling of terminals reporting a zero width. For terminals reporting zero width, the driver now fallbacks to a default width of 80 and a default height of 24 (vt100), as a fallback behaviour. This fixes the crashes and also makes output on "dumb" terminals much more readable.

Own Id: OTP-7592 Aux Id: seq11073

## Erts 5.6.4.1

### Improvements and New Features

A new erts_alloc parameter +M<S>rmbcmt (relative multiblock carrier move threshold) has been added. It determines when to force a moving realloc in a multiblock carrier when a block is shrunk. For more information see the erts_alloc(3) documentation.

Own Id: OTP-7540

The new option +d can be given to erl to suppress the crash dump generation if an internal error is detected. As a result, a more useful core dump is produced.

Own Id: OTP-7578 Aux Id: seq11052

## Erts 5.6.4

### Fixed Bugs and Malfunctions

Double backslashes in format string passed to the erts internal printf implementation produced erroneous results. No such format strings were passed to the erts internal printf implementation, i.e., the bug was therefore completely harmless. (Thanks to Perry Smith.)

Own Id: OTP-7408

Large files are now handled on Windows, where the filesystem supports it.

Own Id: OTP-7410

Bug fixed for {packet,http} when space follows http headers.

Own Id: OTP-7458

The trace option running could cause an emulator crash if the current function couldn't be determined.

Own Id: OTP-7484

Using 16#ffffFFFF as a timeout value in receive...after would often cause a timeout almost at once due to an 32-bit integer overflow. (Thanks to Serge Aleynikov and Matthias Lang.)

Own Id: OTP-7493

For the process that an escript runs in, the trap_exit process flag is now false instead of true (as in previous releases). Scripts that depend on the previous (counter-intuitive) behaviour might not work. (Thanks to Bengt Kleberg.)

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7517

A bug in the string:to_integer/1 builtin made the emulator unstable. This is now corrected. (Thanks to Lev Walkin.)

Own Id: OTP-7526

### Improvements and New Features

Performance for ETS intensive applications should now be better in the SMP emulator. Also, ETS table identifiers (as returned by ets:new/2) are now spread out in wider range than before (using 28 bits in a 32-bit emulator) to make sure that the table identifier for a deleted table will not be quickly re-used.

NOTE: Table identifiers can now be negative integers. Programs that (incorrectly) assume that table identifiers can only be positive integers might stop to work. (The type of a table identifier is intentionally not documented, and may change in a future release.)

Own Id: OTP-7348

New BIF erlang:decode_packet/3 that extracts a protocol packet from a binary. Similar to the socket option {packet, Type}. Also documented the socket packet type http and made it official. NOTE: The tuple format for http packets sent from an active socket has been changed in an incompatible way.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7404

The source code for the documentation for some applications (erts, kernel, stdlib, and several others) are now included in the source tar ball. There is currently no Makefile support for building HTML files from the source (such support will be included in a future release).

Own Id: OTP-7406

A lot of frequently accessed memory counters (erts internal) have been removed. This since they hurt performance on the runtime system with SMP support. As a result erlang:memory/[0,1] will only deliver a result if all erts_alloc(3) allocators are enabled (default). The result delivered when all erts_alloc(3) allocators are enabled are both more accurate and less accurate than before. More memory than before are included in the result, but the different parts that are summed are not gathered atomically. A call to erlang:memory/[0,1] is much cheaper for the system than before. This since the information isn't gathered atomically anymore which was very expensive.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7468

Pre-allocators used for, for example, timers, and messages have been rewritten to be scheduler specific. That is, different schedulers will now allocate from different pools which reduces lock contention.

Own Id: OTP-7470

On Mac OS X, file:sync/1 now guarantees that all filesystem buffers are written to the disk by using the fcntl() with F_FULLFSYNC option. Previously, file:sync/1 called fsync(), which only guaranteed that the data had been transferred to the disk drive. (Thanks to Jan Lehnardt.)

Own Id: OTP-7471

Termination of a process that takes a long time can now be preempted, i.e., the terminating process will be rescheduled for later continuation of termination so that other processes can execute. Termination of a process that owns many and/or large ets tables typically takes a long time.

Own Id: OTP-7477

A new trace option exiting has been added. The exiting trace is similar to the running trace, but for exiting processes. For more information see the erlang(3) documentation.

The erlang:trace/3 bif now doesn't block other scheduler threads if only one tracee is specified in the call to erlang:trace/3.

Own Id: OTP-7481

The re module is extended with repetitive matches (global option) and replacement function.

Own Id: OTP-7494 Aux Id: OTP-7181

In the section about binary construction, the reference manual now mentions what happens when an integer value does not fit into an integer segment of size N (namely, that the N least significant bits will be put into into the binary and that the most significant bits will be silently discarded). (Thanks to Edwin Fine.)

Own Id: OTP-7506

Setting the {active,once} for a socket (using inets:setopts/2) is now specially optimized (because the {active,once} option is typically used much more frequently than other options).

Own Id: OTP-7520

### Known Bugs and Problems

Floating point arithmetics in drivers can cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

Own Id: OTP-7237

## Erts 5.6.3.3

### Fixed Bugs and Malfunctions

Binary construction with an integer field of size 0 at the end of the constructed binary (and the size given in a variable), would cause a write of one byte outside the memory reserved for the binary, which in turn could cause an emulator crash.

Own Id: OTP-7422

A race condition in the dynamic driver implementation could cause an emulator crash. (Thanks to Paul Fisher)

Own Id: OTP-7464

Calls to erlang:system_info(allocated_areas) could cause the runtime system with SMP support to crash.

Own Id: OTP-7474

The env option to open_port() could cause the runtime system with SMP support to crash.

Own Id: OTP-7475

### Improvements and New Features

Operations that needed to block other threads in the runtime system with SMP support unnecessarily waited for async threads to block. Most important the erlang:memory/[0,1] bif, code loading, and the erlang:trace/3 bif.

Own Id: OTP-7480

## Erts 5.6.3.2

### Fixed Bugs and Malfunctions

Calls to erlang:memory/[0,1] could cause the runtime system with SMP support to crash.

Own Id: OTP-7415

## Erts 5.6.3.1

### Fixed Bugs and Malfunctions

Doing local call trace on bit syntax matching code that has been optimized with delayed sub-binary creation could crash the emulator.

Own Id: OTP-7399 Aux Id: seq10978

## Erts 5.6.3

### Fixed Bugs and Malfunctions

Only one to_erl process at a time is allowed to connect to the same run_erl pipe. Prevents buggy behaviour when IO from several to_erl's get interleaved.

Own Id: OTP-5107

IPv6 name resolving has now been fixed to use getaddrinfo() patch (thoroughly reworked) courtesy of Love Hörnquist-Åstrand submitted by Fredrik Thulin. It also can use gethostname2() patch (also reworked) courtesy of Mikael Magnusson for debian submitted by Sergei Golovan.

Own Id: OTP-5382

Improved error handling in run_erl

Own Id: OTP-7252

A permanent fix for the deadlock issue temporarily fixed by OTP-7260.

OTP-7260 The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.

Own Id: OTP-7267 Aux Id: OTP-7260

./configure has been improved to find 64-bit OpenSSL libraries.

Own Id: OTP-7270

A terminating process could under very rare circumstances trigger a bug which could crash the runtime system with SMP support.

Own Id: OTP-7272

SCTP_ADDR_CONFIRMED events are now handled by gen_sctp.

Own Id: OTP-7276

binary_to_term/1 would crash the emulator if the binary data contained an external fun with non-atom module and/or function. Corrected to generate a badarg exception.

Own Id: OTP-7281

On Mac OS 10.5 (Leopard), sending to socket which the other end closes could cause the emulator to consume 100% CPU time. (Thanks to Matthias Radestock.)

Own Id: OTP-7289

The vanilla driver used on Windows could crash the emulator and sometimes produced corrupt files. The vanilla driver is the driver that is used when one only pass a filename as first argument to open_port/2. NOTE: This use of open_port/2 is obsolete, and the documentation of this use has previously been removed. The functionality is only present for backward compatibility reasons and will eventually be removed.

Own Id: OTP-7301

Faulty matching in binaries larger than 512Mb on 64bit machines fixed.(On 32bit, the size limit for binaries is still 512Mb). Thanks to Edwin Fine and Per Gustafsson for finding fault and fix.

Own Id: OTP-7309

crypto:start() on Windows caused emulator to hang on error popup window if openssl DLL was not found. Windows error popups now suppressed.

Own Id: OTP-7325

Configuration option without-termcap can be used to disable the use of termcap libraries for terminal cursor control in the shell.

Own Id: OTP-7338

to_erl reports its terminal window size to run_erl in order to get output formatted accordingly

Own Id: OTP-7342

On Solaris, the compressed option for file operations did not work if the file descriptor happened to be greater than 255 (a problem with fopen() and friends in Solaris itself).

Own Id: OTP-7343 Aux Id: seq10949

A race condition in the runtime system with SMP support causing an erroneous removal of a newly created ets table has been fixed.

The race occurred when a process removed a table during termination simultaneously as another process removed the same table via ets:delete/1 and a third process created a table that accidentally got the same internal table index as the table being removed.

Own Id: OTP-7349

zlib:inflate failed when the size of the inflated data was an exact multiple of the internal buffer size (4000 bytes by default).

Own Id: OTP-7359

If the total number of allowed atoms is exceeded, there will now be a controlled termination of the emulator with a crash dump file. The emulator used to simply crash. (Thanks Howard Yeh and Thomas Lindgren.)

Own Id: OTP-7372

The break handler in werl on Windows could cause the emulator to hang or crash, that is now corrected.

Own Id: OTP-7394 Aux Id: seq10969

The configure script now tests for an serious optimization bug in gcc-4.3.0. If the bug is present, the configure script will abort (if this happens, the only way to build Erlang/OTP is to change to another version of gcc). (Thanks to Mikael Pettersson.)

Own Id: OTP-7397

### Improvements and New Features

On Unix, the emulator now notices when the width of the terminal has changed. (Thanks to Matthew Dempsky and Patrick Mahoney.)

Own Id: OTP-7290

There is a new function init:stop/1 which can be used to shutdown the system cleanly AND generate a non-zero exit status or crash dump. (Thanks to Magnus Froberg.)

Own Id: OTP-7308

process_info(Pid, garbage_collection) now returns more information

Own Id: OTP-7311

The hide option for open_port/2 is now documented. (Thanks to Richard Carlsson.)

Own Id: OTP-7358

### Known Bugs and Problems

Floating point arithmetics in drivers can cause a runtime system crash on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

Own Id: OTP-7237

## Erts 5.6.2

### Fixed Bugs and Malfunctions

The maximum length of an atom of 255 characters is now strictly enforced. binary_to_term/1 will now fail with a badarg if an encoded term contains an atom longer than 255 characters. Atoms created by drivers will now be truncated to 255 characters if necessary. (Thanks to Matthew Dempsky.)

Own Id: OTP-7147

A bug in "bignum handling" on some 64bit architectures could cause rem and div operations on large numbers to hang indefinitely. Rem operations involving the smallest negative number representable in 28 bits or 60 bits could also cause access violation and emulator crash. Both errors are corrected.

Own Id: OTP-7177

When doing the initial garbage collection after waking a hibernated process, a fullsweep garbage collection was unnecessarily triggered.

Own Id: OTP-7212

The beta testing module gen_sctp now supports active mode as stated in the documentation. Active mode is still rather untested, and there are some issues about what should be the right semantics for gen_sctp:connect/5. In particular: should it be blocking or non-blocking or choosable. There is a high probability it will change semantics in a (near) future patch.

Try it, give comments and send in bug reports!

Own Id: OTP-7225

Invalid arguments to ets:update_counter/3 were not handled correctly. A tuple position (Pos) less than 1 caused the element directly following the key to be updated (as if no position at all had been specified). All invalid values for Pos will now fail with badarg.

Own Id: OTP-7226

The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.

Own Id: OTP-7260

### Improvements and New Features

More checksum/hash algorithms from the zlib library are now available as built in functions (like md5 hashes has been for a long time).

Own Id: OTP-7128

Minor improvements in the garbage collector.

Own Id: OTP-7139 Aux Id: OTP-7132

The switch "-detached" to the windows werl program now can create an erlang virtual machine without any main window and without a temporary console showing.

Own Id: OTP-7142

erlang:system_info/1 now accepts the logical_processors, and debug_compiled arguments. For more info see the, erlang(3) documentation.

The scale factor returned by test_server:timetrap_scale_factor/0 is now also effected if the emulator uses a larger amount of scheduler threads than the amount of logical processors on the system.

Own Id: OTP-7175

A new BIF ets:update_element/3. To update individual elements within an ets-tuple, without having to read, update and write back the entire tuple.

Own Id: OTP-7200

A process executing the processes/0 BIF can now be preempted by other processes during its execution. This in order to disturb the rest of the system as little as possible. The returned result is, of course, still a consistent snapshot of existing processes at a time during the call to processes/0.

The documentation of the processes/0 BIF and the is_process_alive/1 BIF have been updated in order to clarify the difference between an existing process and a process that is alive.

Own Id: OTP-7213

## Erts 5.6.1.1

### Fixed Bugs and Malfunctions

Not enough parameters were passed when sending an error report in erl_check_io.c (Thanks to Matthew Dempsky).

Own Id: OTP-7176

In rare circumstances, complex binary matching code could cause the emulator to crash or not match when it should. (Thanks to Rory Byrne.)

Own Id: OTP-7198

### Improvements and New Features

The {allocator_sizes, Alloc} and alloc_util_allocators arguments are now accepted by erlang:system_info/1. For more information see the erlang(3) documentation.

Own Id: OTP-7167

The finishing reallocation of the heap block when hibernating a process is now always moving the heap block since it drastically reduces memory fragmentation when hibernating large amounts of processes.

Own Id: OTP-7187

## Erts 5.6.1

### Fixed Bugs and Malfunctions

The SMP emulator on sparc64 erroneously used the sparc32 atomic and the sparc32 spinlock implementations which caused it to crash.

Own Id: OTP-7006

Call tracing the new guard BIFs byte_size, bit_size, or tuple_size and the loading a module that uses one of those functions, could cause the emulator to terminate.

Own Id: OTP-7008

configuring --enable-darwin-universal or --enable-darwin-64bit on MacOSX could result in a non optimized emulator. Top level configure script now corrected.

Own Id: OTP-7014

configuring --with-gd did not produce correct include flags for percept.

Own Id: OTP-7015

Environment variables weren't handled in thread safe manner in the runtime system with SMP support on Windows.

erl_drv_putenv(), and erl_drv_getenv() has been introduced for use in drivers. Do not use putenv(), or getenv() directly in drivers. For more information see the erl_driver documentation.

Own Id: OTP-7035

HIPE: Corrected the choice of interface to the send/3 and setnode/3 BIFs for native-compiled code. Using the incorrect interface could, in unusual circumstances, lead to random runtime errors.

Own Id: OTP-7067

Garbage collections could become extremely slow when there were many keys in the process dictionary. (Thanks to Fredrik Svahn.)

Own Id: OTP-7068

The duplicate documentation directory in the windows installation is removed.

Own Id: OTP-7070

Documentation bugfixes and clarifications.

(Thanks to Joern (opendev@gmail.com), Matthias Lang, and Richard Carlsson.)

Own Id: OTP-7079

The runtime system with SMP support not using the native atomic integer implementation part of OTP could deadlock when run on a system with more than one logical processor. That is, only the runtime system with SMP support on other hardware platforms than x86, x86_64, sparc32, and powerpc32 were effected by this bug.

Own Id: OTP-7080

The break handling code (run when Ctrl-C is hit) could could potentially deadlock the runtime system with SMP support.

Own Id: OTP-7104

The sctp driver has been updated to work against newer lksctp packages e.g 1.0.7 that uses the API spelling change adaption -> adaptation. Older lksctp (1.0.6) still work. The erlang API in gen_sctp.erl and inet_sctp.hrl now spells 'adaptation' regardless of the underlying C API.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7120

A bug in erlang:phash2/1 on 64-bit platforms has been fixed. (Thanks to Scott Lystig Fritchie.)

Own Id: OTP-7127

The emulator could under rare circumstances crash while garbage collecting.

Own Id: OTP-7132

### Improvements and New Features

The documentation has been updated so as to reflect the last updates of the Erlang shell as well as the minor modifications of the control sequence p of the io_lib module.

Superfluous empty lines have been removed from code examples and from Erlang shell examples.

Own Id: OTP-6944 Aux Id: OTP-6554, OTP-6911

Bit syntax construction with a small integer in a non-byte aligned field wider than the CPU's word size could cause garbage bits in the beginning of the field.

Own Id: OTP-7085

All Windows versions older than Windows 2000 are now not supported by the Erlang runtime system. This since there was a need for usage of features introduced in Windows 2000.

Own Id: OTP-7086

Memory management improvements especially for the runtime system with SMP support:

The runtime system with SMP support can now use multiple, thread specific instances of most memory allocators. This improves performance since it reduces lock contention in the memory allocators. It may however increase memory usage for some applications. The runtime system with SMP support will by default enable this feature on most allocators. The amount of instances used can be configured. driver_alloc(), driver_realloc(), and driver_free() now use their own erts specific memory allocator instead of the default malloc() implementation on the system. The default configuration of some allocators have been changed to fit applications that use much memory better. Some new erts_alloc configuration parameters have been added. erts_alloc_config has been modified to be able to create configurations suitable for multiple instances of allocators. The returned value from erlang:system_info({allocator, Alloc}) has been changed. This since an allocator may now run in multiple instances.

If you for some reason want the memory allocators to be configured as before, you can pass the +Mea r11b command-line argument to erl.

For more information see the erts_alloc(3), the erts_alloc_config(3), and the erlang(3) documentation.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7100

On Unix, denormalized floating point numbers could not be created using list_to_float/1 or binary_to_term/1. (Thanks to Matthew Dempsky.)

Own Id: OTP-7122

Native atomic integers and spin-locks are now also available for the runtime system with SMP support on sparc64.

Own Id: OTP-7130

FP exceptions support for sparc64 userspace on Linux has been added. Note that FP exception support is now turned off by default, so to actually enable it you need to do './configure --enable-fp-exceptions'.

Own Id: OTP-7131

## Erts 5.6

### Fixed Bugs and Malfunctions

A bug for raw files when reading 0 bytes returning 'eof' instead of empty data has been corrected.

Own Id: OTP-6291 Aux Id: OTP-6967

All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.

Own Id: OTP-6816 Aux Id: OTP-6591

On the 64-bit Erlang emulator, bit syntax construction with integers containing more than 60 bits ("big numbers") into fields with more than 60 bits could produce incorrect results.

Own Id: OTP-6833

When the runtime system failed to allocate memory for binaries, it could dead lock while writing the erl_crash.dump.

Own Id: OTP-6848

The runtime system with SMP support could deadlock if a process called the erlang:suspend_process(Pid) BIF or the erlang:garbage_collect(Pid) BIF while the process identified by Pid was currently running and the process calling the BIFs was terminated during the call to the BIFs.

Processes suspending each other via the erlang:suspend_process/1 BIF or garbage collecting each other via the erlang:garbage_collect/1 BIF could deadlock each other when the runtime system with SMP support was used.

Own Id: OTP-6920

dbg could leave traced processes in a suspended state if the tracer process was killed with exit reason kill.

erlang:suspend_process/2 has been introduced which accepts an option list as second argument. For more information see the erlang(3) documentation.

Processes suspended via erlang:suspend_process/[1,2] will now be automatically resumed if the process that called erlang:suspend_process/[1,2] terminates.

Processes could previously be suspended by one process and resumed by another unless someone was tracing the suspendee. This is not possible anymore. The process resuming a process has to be the one that suspended it.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6946

file:write_file/3, file:write/2 and file:read/2 could crash (contrary to documentation) for odd enough file system problems, e.g write to full file system. This bug has now been corrected.

In this process the file module has been rewritten to produce better error codes. Posix error codes now originate from the OS file system calls or are generated only for very similar causes (for example 'enomem' is generated if a memory allocation fails, and 'einval' is generated if the file handle in Erlang is a file handle but currently invalid).

More Erlang-ish error codes are now generated. For example {error,badarg} is now returned from file:close/1 if the argument is not of a file handle type. See file(3).

The possibility to write a single byte using file:write/2 instead of a list or binary of one byte, contradictory to the documentation, has been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6967 Aux Id: OTP-6597 OTP-6291

Monitor messages produced by the system monitor functionality, and garbage collect trace messages could contain erroneous heap and/or stack sizes when the actual heaps and/or stacks were huge.

As of erts version 5.6 the large_heap option to erlang:system_monitor/[1,2] has been modified. The monitor message is sent if the sum of the sizes of all memory blocks allocated for all heap generations is equal to or larger than the specified size. Previously the monitor message was sent if the memory block allocated for the youngest generation was equal to or larger than the specified size.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6974 Aux Id: seq10796

inet:getopts/2 returned random values on Windows Vista.

Own Id: OTP-7003

### Improvements and New Features

The emulator internal process lock implementation has been rewritten and optimized. A slight risk of starvation existed in the previous implementation. This risk has also been eliminated in the new implementation.

Own Id: OTP-6500

Bitstrings (bit-level) binaries and binary comprehensions are now part of the language. See the Reference Manual.

Own Id: OTP-6558

The windows version of erlang now has SMP support. The SMP emulator is run by default on machines which shows more than one virtual or physical processor.

Own Id: OTP-6560 Aux Id: OTP-6925

The details of the compressed term format has been documented in erl_ext_dist.txt. (Thanks to Daniel Goertzen.)

Own Id: OTP-6755

The runtime system with SMP support is now started by default if more than one logical processor are detected. For more information, see the erl(3) documentation.

Own Id: OTP-6756

The external format for Erlang terms and the distribution protocol are now documented in ERTS User's Guide.

Own Id: OTP-6779

New BIF's erlang:system_profile/1 and erlang:system_profile/2. These BIF's controls concurrency profiling options for processes, ports and schedulers.

Own Id: OTP-6783 Aux Id: OTP-6285

The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_BUF2BINARY, ERL_DRV_EXT2TERM, and ERL_DRV_UINT. ERL_DRV_BUF2BINARY is used for passing and creating a binary, ERL_DRV_EXT2TERM is used for passing terms encoded with the external term format, and ERL_DRV_UINT is used for passing unsigned integers.

Also the data types ErlDrvUInt and ErlDrvSInt have been added which makes it more obvious how arguments to term types are interpreted with regards to width and signedness.

The incorrect data types ErlDriverTerm, ErlDriverBinary, and ErlDriverPort in the erl_driver(3) documentation have been replaced with the correct data types ErlDrvTermData, ErlDrvBinary, and ErlDrvPort.

For more information see the erl_driver(3) documentation.

Own Id: OTP-6823

Miscellaneous improvements of the erts internal thread library.

It now support optimized atomic operations and spin-locks on windows.

Fall-backs based on mutexes and/or spin-locks for missing optimized atomic operations, spin-locks, or rwlocks has been implemented. This makes it possible to compile the runtime system with SMP support on a lot more platforms.

Default stack size on OpenBSD has been increased to 256 kilo-words.

Own Id: OTP-6831 Aux Id: OTP-6560

Many bit syntax operations, both construction and matching, are faster. For further information, see the Efficiency Guide.

Own Id: OTP-6838

Literal lists, tuples, and binaries are no longer constructed at run-time as they used to be, but are stored in a per-module constant pool. Literals that are used more than once are stored only once.

This is not a change to the language, only in the details of its implementation. Therefore, the implications of this change is described in the Efficiency Guide.

Example 1: In the expression element(BitNum-1, {1,2,4,8,16,32,64,128}), the tuple used to be constructed every time the expression was executed, which could be detrimental to performance in two ways if the expression was executed in a loop: the time to build the tuple itself and the time spent in garbage collections because the heap filled up with garbage faster.

Example 2: Literal strings, such as "abc", used to be stored in the compiled code compactly as a byte string and expanded to a list at run-time. Now all strings will be stored expanded to lists (such as [$a,$b,$c]) in the constant pool. That means that the string will be faster to use at run-time, but that it will require more space even when not used. If space is an issue, you might want to use binary literals (that is, <<"abc">>) instead of string literals for infrequently used long strings (such as error messages).

Own Id: OTP-6850

The Erlang driver API has been extended with a portable POSIX thread like API for multi-threading. The Erlang driver thread API provides:

Threads Mutexes Condition variables Read/Write locks Thread specific data

For more information see the erl_driver(3) documentation.

Own Id: OTP-6857

Recursive calls now usually consume less stack than in R11B. See the Efficiency Guide.

Own Id: OTP-6862 Aux Id: seq10746

The deprecated BIFs erlang:old_binary_to_term/1 and erlang:info/1 have been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6876

Calls to driver call-backs triggered by external events are now scheduled and interleaved with execution of Erlang processes also on the runtime system without SMP support.

Own Id: OTP-6878

Faster arithmetic of integers of more than 27 bits signed (or 60 bits signed on an 64-bit CPU), and also faster integer multiplication. (Thanks to Tony Rogvall.)

Own Id: OTP-6891

Significant improvements of the process_info BIFs:

process_info/2 can now be called with a list of items as second argument in order to atomically retrieve information about multiple items. process_info/[1,2] has been optimized in the runtime system with SMP support. The whole scheduler could previously be blocked for a significant period of time in process_info/[1,2] waiting for a lock on the process being inspected. The Erlang process calling process_info/[1,2] can still be blocked for a significant period of time waiting for the lock, but the scheduler will now be able to run other processes while the process calling process_info/[1,2] waits for the lock. process_info/2 now accept a few more items than before. The documentation of process_info/[1,2] has been improved.

For more information see the erlang(3) documentation.

Own Id: OTP-6899

open_port({}, []) could crash the emulator. (Thanks to Matthew Dempsky.)

Own Id: OTP-6901

Two new guard BIFs have been introduced as a recommended replacement for size/1. (The size/1 BIF will be removed no earlier than in R14B.) The BIFs are tuple_size/1 to calculate the size of a tuple and byte_size/1 to calculate the number of bytes needed for the contents of the binary or bitstring (rounded up to the nearest number of bytes if necessary).

There is also a new bit_size/1 BIF that returns the exact number of bits that a binary or bitstring contains.

Own Id: OTP-6902

The ets:fixtable/2 function, which has been deprecated for several releases, has been removed.

The ets:info/1 function has been reimplemented as a BIF, which guarantees that information returned is consistent.

The ets:info/2 function now fails with reason badarg if the second argument is invalid. (Dialyzer can be used to find buggy code where the second argument is misspelled.)

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6906

As the linux kernel may generate a minor fault when tracing with CPU timestamps, and there exists no patch to the Linux kernel that fixes the problem, cpu timestamps are disabled on Linux for now.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6922

The functions io:columns/0, io:columns/1, io:rows/0 and io:rows/1 are added to allow the user to get information about the terminal geometry. The shell takes some advantage of this when formatting output. For regular files and other io-devices where height and width are not applicable, the functions return {error,enotsup}.

Potential incompatibility: If one has written a custom io-handler, the handler has to either return an error or take care of io-requests regarding terminal height and width. Usually that is no problem as io-handlers, as a rule of thumb, should give an error reply when receiving unknown io-requests, instead of crashing.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6933

driver_caller() can now also be used from the start callback of a driver.

Own Id: OTP-6951

The emulator can now be compiled for 64bit intel, as well as a 32bit universal binary on darwin/MacOSX 10.4 and 10.5.

Own Id: OTP-6961

If open_port fails because all available ports are already in use, it will now throw a system_limit exception instead of an enfile exception. (enfile might still be thrown if the operating system would return ENFILE.)

Own Id: OTP-6968

The spawn_monitor/1 and spawn_monitor/3 BIFs are now auto-imported (i.e. they no longer need an erlang: prefix).

Own Id: OTP-6975

On Windows, the werl window now handles resize, so that the whole window can be utilized. Text selection is also updated to be line oriented instead of rectangle oriented as in earlier versions.

Own Id: OTP-6994 Aux Id: OTP-6933

Kqueue support (kernel-poll) has been enabled on FreeBSD. The problem with kqueue not detecting writes on a pipe on FreeBSD was actually not a kqueue issue, but a writev on pipes issue. Neither poll(), nor select() detected the write when the bug hit. NetBSD and DragonFlyBSD probably have or have had the same bug. This bug should have been fixed in FreeBSD 6.3 and FreeBSD 7.0 thanks to Jean-Sebastien Pedron.

Own Id: OTP-7001

## Erts 5.5.5.5

### Fixed Bugs and Malfunctions

Hanging writes on temporarily unavailable NFS filesystems could cause the execution of (not file related) erlang code to get blocked even though I/O threads were used. This is now corrected.

Own Id: OTP-6907 Aux Id: seq10771

## Erts 5.5.5.4

### Fixed Bugs and Malfunctions

Data passed to a driver via erlang:port_call could be corrupted when the runtime system with SMP support was used. (Thanks to YAMASHINA Hio.)

Own Id: OTP-6879

In the SMP emulator, if several processes called ets:update_counter/3 (even for different tables) when the counter values exceeded 27 bits, the counter values could be corrupted or the emulator could crash.

Own Id: OTP-6880 Aux Id: seq10760

## Erts 5.5.5.3

### Fixed Bugs and Malfunctions

Creating a named table using ets:new/2 or renaming a named table using ets:rename/2 could in rare circumstances succeed, meaning that there would be two or more tables with the same name. Now such call will fail with a badarg exception as it is supposed to do.

ets:delete/1 used on a named table now removes the name immediately so that a new table with the same name can be created.

Turning on call trace on the internal BIF that implements ets:delete/1 would crash the emulator.

SMP emulator only: Using ets:rename/2 on a table that ets:safe_fixtable/2 has been used on could cause an emulator crash or undefined behaviour because of a missing lock.

Own Id: OTP-6872 Aux Id: seq10756, seq10757

## Erts 5.5.5.2

### Known Bugs and Problems

ets:select/3 on ordered_set and with a chunksize a multiple of 1000 gave all elements instead of just 1000. Also ets:slot/2 on ordered set could give unexpected results on SMP emulator. Both problems are corrected.

Own Id: OTP-6842

## Erts 5.5.5.1

### Fixed Bugs and Malfunctions

All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.

Own Id: OTP-6816 Aux Id: OTP-6591

Calling binary_to_term/1 with certain invalid binaries would crash the emulator.

Own Id: OTP-6817

### Improvements and New Features

Restored speed of bit-syntax matching of 32 bits integers.

Own Id: OTP-6789 Aux Id: seq10688

## Erts 5.5.5

### Fixed Bugs and Malfunctions

The functions in gzio.c have been renamed to avoid conflict with drivers that indirectly linked with an external zlib library.

Own Id: OTP-6591

The emulator without SMP support dumped core if an async-thread finished a job after the emulator had begun writing an erl_crash.dump.

Own Id: OTP-6685

In bit syntax matching, integer fields with greater size than 16Mb would fail to match. (Thanks to Bertil Karlsson and Francesco Pierfederici.)

Matching out a 32-bit integer not aligned on a byte boundary from a binary could cause an heap overflow (and subsequent termination of the emulator).

A module that contained bit syntax construction with a literal field size greater than 16Mb would fail to load.

Several other similar bugs having to do with huge field sizes were eliminated.

Attempting to construct a binary longer than 536870911 bytes will now fail with a system_limit exception (rather than fail in mysterious ways or construct an binary with incorrect contents). Similarily, attempting to match a binary longer than 536870911 bytes will now fail (instead of producing an incorrect result). This limitation has been documented in the Efficiency Guide. (The limit is in the 32-bit emulator; use the 64-bit emulator if you need to handle larger binaries than 536870911.)

Own Id: OTP-6686

Bugs in rem and div of very large numbers are corrected.

Own Id: OTP-6692

erlang:system_info({allocator, Alloc}) didn't allocate enough heap when a bignum was part of the result which could cause an emulator crash.

Own Id: OTP-6693

It was previously not possible to pass erts_alloc the same configuration via the command-line, as used by default.

A +M* command-line argument that configure a size of some sort can now be passed a value that equals the size of the address space. The value used, in this case, will be "the size of the address space" - 1.

Own Id: OTP-6699

SysIOVec* driver_peekq(ErlDrvPort port, int *vlen) did not update *vlen if port was invalid. *vlen is now set to -1 if the port is invalid.

The efile driver expects *vlen to be updated also when the port is invalid. This situation occurs seldom, but when the runtime system has async-threads enabled and ports are killed it can. When it occurred the runtime system crashed.

Own Id: OTP-6729

### Improvements and New Features

For scripts written using escript, there is a new function escript:script_name/0, which can be used to retrieve the pathame of the script. The documentation has been clarified regarding pre-defined macros such as ?MODULE and the module name.

Own Id: OTP-6593

The section Guards in the chapter The Abstract Format of the ERTS User's Guide has been updated.

Own Id: OTP-6600

Corrected protocol layer flue for socket options SO_LINGER, SO_SNDBUF and SO_RCVBUF, for SCTP.

Own Id: OTP-6625 Aux Id: OTP-6336

The behaviour of the inet option {active,once} on peer close is improved and documented.

Own Id: OTP-6681

The inet option send_timeout for connection oriented sockets is added to allow for timeouts in communicating send requests to the underlying TCP stack.

Own Id: OTP-6684 Aux Id: seq10637 OTP-6681

The command line flag -args_file FileName, and the environment variables ERL_AFLAGS, and ERL_ZFLAGS for the erl command have been added. For more information see the erl(1) documentation.

Own Id: OTP-6697

The is_constant/1 type test has been deprecated. is_constant/1 is improperly named and almost entirely undocumented.

Own Id: OTP-6731

## Erts 5.5.4.3

### Fixed Bugs and Malfunctions

process_flag(trap_exit, Bad) where Bad was a term not equal to true or false, didn't fail with badarg as it should; instead, the failure was silently ignored. This bug was introduced in erts-5.5.2.

Own Id: OTP-6627 Aux Id: OTP-6160

The minimum and default stack size for async-threads has been increased to 16 kilowords. This since the previous minimum and default stack size of 8 kilowords proved to be too small (introduced in erts-5.5.4.2).

Own Id: OTP-6628 Aux Id: OTP-6580, Seq10633

### Improvements and New Features

process_flag/2 accepts the new flag sensitive.

Own Id: OTP-6592 Aux Id: seq10555

## Erts 5.5.4.2

### Fixed Bugs and Malfunctions

When a port steals control over a file descriptor from another port, the stealing port tests if the other port is alive. This in order to be able to give an accurate error message. In the runtime system with SMP support, this test was done without appropriate locks held. This could in worst case lead to an erroneous error message; therefore, this bug is to be considered harmless.

Own Id: OTP-6602

### Improvements and New Features

The default stack size for threads in the async-thread pool has been shrunk to 8 kilowords, i.e., 32 KB on 32-bit architectures. This small default size has been chosen since the amount of async-threads might be quite large. The default stack size is enough for drivers delivered with Erlang/OTP, but might not be sufficiently large for other dynamically linked in drivers that use the driver_async() functionality. A suggested stack size for threads in the async-thread pool can be configured via the +a command line argument of erl(1).

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6580

## Erts 5.5.4.1

### Fixed Bugs and Malfunctions

Setting the time on the system while using heart on a linux machine where the emulator was built with clock_gettime support (default from Linux 2.6/erts-5.5.4 and upwards), could make the heart command fire. This was due to bug in the heart executable which is now corrected.

Own Id: OTP-6598 Aux Id: seq10614

## Erts 5.5.4

### Fixed Bugs and Malfunctions

Corrected misspelling of '-pz' in the help text for erlc. (Thanks to Ulf Wiger.)

Own Id: OTP-6433

The MD5 calculation of a BEAM file done by code:module_md5/1, beam_lib:md5/1, and by the compiler for the default value of the vsn attribute have all been changed so that its result will be the same on all platforms; modules containing funs could get different MD5s on different platforms.

Own Id: OTP-6459

The emulator could dump core while writing an erl_crash.dump file if there were funs with a large terms in its environment. Since there is no way to inspect a fun's environment in the crashdump_viewer application anyway, a variables in the environment are now set to [] before dumping the fun. (Thanks to Jean-Sebastien Pedron.)

Own Id: OTP-6504

{Port, {exit_status, S}} messages from ports opened with the exit_status option could under rare circumstances be delayed. This bug was present on Erlang runtime systems without SMP support on all unix operating systems other than SunOS.

Own Id: OTP-6528

A bug in linuxthreads could cause the emulator to dump core when dlerror() was called before the first call to dlopen(). As a workaround the emulator always makes a call to dlopen() on initialization when linuxthreads is used as thread library.

Own Id: OTP-6530

file:sync/1 did not do anything on Windows. Now it calls the system function for flushing buffers (FlushFileBuffers()). (Thanks to Matthew Sackman.)

Own Id: OTP-6531

open_port/2 could on the runtime system with SMP support fail with the wrong exit reason when a port couldn't be created. When this happened the exit reason was typically eintr, or ebusy instead of eagain.

Own Id: OTP-6536

The file driver (efile_drv) did not flush data written using the option 'delayed_write' after the set timeout time, rather at the next file operation. This bug has now been corrected.

Own Id: OTP-6538

### Improvements and New Features

An interface towards the SCTP Socket API Extensions has been implemented.It is an Open Source patch courtesy of Serge Aleynikov and Leonid Timochouk. The Erlang code parts has been adapted by the OTP team, changing the Erlang API somewhat.

The Erlang interface consists of the module gen_sctp and an include file -include_lib("kernel/include/inet_sctp.hrl"). for option record definitions. The gen_sctp module is documented.

The delivered Open Source patch, before the OTP team rewrites, was written according to http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13 and was claimed to work fine, tested on Linux Fedora Core 5.0 (kernel 2.6.15-2054 or later) and on Solaris 10 and 11. The OTP team rewrites used the same standard document but might have accidentally broken some functionality. If so it will soon be patched to working state. The tricky parts in C and the general design has essentially not changed. During the rewrites the code was hand tested on SuSE Linux Enterprise Server 10, and briefly on Solaris 10. Feedbach on code and docs is very much appreciated.

The SCTP interface is in beta state. It has only been hand tested and has no automatic test suites in OPT meaning everything is most certainly not tested. Socket active mode is broken. IPv6 is not tested. The documentation has been reworked due to the API changes, but has not been proofread after this.

Thank you from the OTP team to Serge Aleynikov and Leonid Timochouk for a valuable contribution. We hope we have not messed it up too much.

Own Id: OTP-6336

A {minor_version,Version} option is now recognized by term_to_binary/2. {minor_version,1} will cause floats to be encoded in an exact and more space-efficient way compared to the previous encoding.

Own Id: OTP-6434

There is a new escript program that can be used for writing scripts in Erlang. Erlang scripts don't need to be compiled and any arguments can be passed to them without risk that they are interpreted by the Erlang system.

Own Id: OTP-6505

Setting and getting socket options in a "raw" fashion is now allowed. Using this feature will inevitably produce non portable code, but will allow setting ang getting arbitrary uncommon options on TCP stacks that do have them.

Own Id: OTP-6519

Miscellaneous signal handling improvements on the Erlang runtime system with SMP support.

The fallback implementation of spin locks and atomic operations are now implemented using pthread spin locks when pthread spin locks are found on the system.

The Erlang runtime system with SMP support can now run on Linux systems that has Linuxthreads instead of NPTL (Native POSIX Thread Library). Note that the SMP support hasn't been as thoroughly tested with Linuxthreads as with NPTL. A runtime system with SMP support will therefore not be built by default on Linux when NPTL isn't found. In order to force a build of the runtime system with SMP support, pass --enable-smp-support to configure when building OTP.

Own Id: OTP-6525

## Erts 5.5.3.1

### Fixed Bugs and Malfunctions

erlang:system_flag(multi_scheduling, block) could cause the emulator with SMP support to deadlock.

Own Id: OTP-6431 Aux Id: OTP-6403

The runtime system with SMP support failed to call the driver timeout callback of ports in state closing. This could cause ports to fail flushing their I/O queues.

Own Id: OTP-6432

The {Port, closed} message from a closed port could arrive at the port owner before Port had been removed from the result of erlang:ports/0 in the runtime system with SMP support.

Own Id: OTP-6437

The async id of async jobs created via driver_async wasn't created in a thread safe manner in the runtime system with SMP support. This could in worst case cause driver_async_cancel() to cancel another async job than intended.

Own Id: OTP-6438

Under rare circumstances a terminating connection between two nodes could cause an instantaneous reconnect between the two nodes to fail on the runtime system with SMP support.

Own Id: OTP-6447

In the documentation of the driver entry field extended_marker of erts version 5.5.3 (driver_entry(3)), the following is stated: "The following fields are ignored if this field is equal to 0". This is a documentation bug and has been changed to: "If this field is equal to 0, all the fields following this field also have to be 0, or NULL in case it is a pointer field".

The runtime check for detection of old incompatible drivers made when loading drivers has been improved. The emulator can, however, not make sure that a driver that doesn't use the extended driver interface isn't incompatible. Therefore, when loading a driver that doesn't use the extended driver interface, there is a risk that it will be loaded also when the driver is incompatible. When the driver use the extended driver interface, the emulator can verify that it isn't of an incompatible driver version. You are therefore advised to use the extended driver interface.

For more information see the erl_driver(3) and driver_entry(3) documentation.

Own Id: OTP-6452 Aux Id: OTP-6330

When terminating ports on the runtime system with SMP support, removal of links to processes was done without locking the link lock on processes. This could cause an emulator crash.

Own Id: OTP-6475

The emulator with SMP support could crash when a port flushed its I/O queue by calling driver_async() from the timeout driver callback.

Own Id: OTP-6479

Large exit reasons could under rare circumstances cause the runtime system with SMP support to crash.

Own Id: OTP-6521

### Improvements and New Features

Faster system calls for keeping the time accurate are used on newer Linux kernels, which can result in a significant speed-up of the emulator on those systems.

Own Id: OTP-6430

Added number of async threads and number of scheduler threads to the system information that can be retrieved via driver_system_info(). For more information see the erl_driver(3) documentation.

Own Id: OTP-6440

When SIGUSR1 is received by the runtime system with SMP support, the erl_crash.dump is now written by a special thread, instead of as before directly from the signal handler.

Own Id: OTP-6465

term_to_binary/2 with compression is now faster.

term_to_binary/2 now accepts the option '{compressed,Level}' for specifying the compression level. Level must be in the range 0 (no compression) through 9 (highest compression level). Default is 6.

Future compatibility bugfix: binary_to_term/1 did not handle the Uniq and Index fields correctly.

Own Id: OTP-6494

Removed unnecessary reallocation when initializing kernel-poll set.

Own Id: OTP-6516

## Erts 5.5.3

### Fixed Bugs and Malfunctions

Node and fun table entries could under rare circumstances be deallocated multiple times on the emulator with SMP support.

Own Id: OTP-6369

epoll_wait() can repeat entries for the same file descriptor in the result array. This could cause the ready_input, ready_output, or event callbacks of a driver to unintentionally be called multiple times. We have only noted repeated entries when an error condition has occurred on the file descriptor. In this case, the repeated entries should normally not be a problem for the driver since it should detect the error and de-select the file descriptor. Therefore this bug should be considered harmless. The emulator now coalesce repeated entries into one.

You are only affected by this bug if you are using erts-5.5.2.* and the kernel-poll feature on linux.

Own Id: OTP-6376 Aux Id: OTP-6222

If a process that was waiting in gen_tcp:accept/1 was killed, calling gen_tcp:accept/1 again on the same listen socket would fail with '{error,einval}'.

Own Id: OTP-6381 Aux Id: seq10535

The emulator failed to start on Solaris 10 when kernel-poll support was enabled and the maximum number of filedescriptors configured was less than or equal to 256.

Own Id: OTP-6384 Aux Id: OTP-6222

The R10B compiler could generate unsafe bs_save/bs_restore instructions that could cause memory corruption. (The R11B compiler does not have that problem.) The erlang emulator will now refuse to load R10B-compiled modules that contain such unsafe bs_save/bs_restore instructions. In addition, the beam_validator module in the compiler will also reject such instructions (in case it is used to validate R10B code). (Thanks to Matthew Reilly.)

Own Id: OTP-6386

Process and port timers could fail to work properly on the runtime system with SMP support. Many thanks to Dmitriy Kargapolov and Serge Aleynikov who tracked down this bug.

Own Id: OTP-6387

Bit syntax code compiled by an R10B compiler that matched out a floating point number would not properly check that the floating point number was valid; if the float was, for instance, NaN the emulator could crash.

Own Id: OTP-6395

statistics(runtime) on Windows used to return the elapsed system time for the process, instead of the user time. Corrected. (Thanks to Robert Virding.)

Own Id: OTP-6407

A loadable driver (loaded by erl_ddll) which used driver_async() would cause the emulator to crash. (Thanks to Dmitriy Kargapolov.)

Own Id: OTP-6410

Under rare circumstances the emulator on unix platforms could fail to terminate the Erlang port corresponding to a port program opened with the exit_status option.

Own Id: OTP-6411

A link removed via unlink/1 could under rare circumstances transfer exit signals for a short period of time after the call to unlink/1 had returned when the runtime system with SMP support was used.

Own Id: OTP-6425 Aux Id: OTP-6160

### Improvements and New Features

In the runtime system with SMP support, ports are now being scheduled on the scheduler threads interleaved with processes instead of being run in a separate I/O thread.

Own Id: OTP-6262

More interfaces are added in erl_ddll, to support different usage scenarios.

Own Id: OTP-6307 Aux Id: OTP-6234

In the runtime system with SMP support, the global I/O lock has been replaced with a more fine grained port locking scheme. Port locking is either done on driver level, i.e., all ports executing the same driver share a lock, or on port level, i.e., each port has its own lock. Currently the inet driver, the efile driver, and the spawn driver use port level locking and all other statically linked in drivers use driver level locking. By default dynamically linked in drivers will use locking on driver level. For more information on how to enable port level locking see the erl_driver(3) and the driver_entry(3) man pages.

As of erts version 5.5.3 the driver interface has been extended. The extended interface introduce version management, the possibility to pass capability flags to the runtime system at driver initialization, and some new driver API functions. For example, the driver_system_info() function which can be used to determine if the driver is run in a runtime system with SMP support or not. The extended interface doesn't have to be used, but dynamically linked in driver have to be recompiled. For information see the erl_driver(3) and the driver_entry(3) man pages.

NOTE: Dynamically linked in drivers have to be recompiled.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6330 Aux Id: OTP-6262

A test and debug feature which modifies the timing of the runtime system has been added. For more information, see documentation of the +T<Level> command line argument of erl(1).

Own Id: OTP-6382

The version of zlib (http://zlib.net) linked into run-time system has been updated to version 1.2.3.

Own Id: OTP-6394

The erlc program now passes on the -smp and -hybrid options to the Erlang emulator it starts. This is mainly useful for compiling native code, because native code must be compiled with same type of run-time system as in which it will be run.

If the -s option is given, erlc now prints a warning that it is deprecated and that it will be removed in R12B.

Own Id: OTP-6398

The schedulers option of erlang:system_flag/2 has been removed, i.e., the number of scheduler threads cannot be changed after emulator boot time any more.

A multi_scheduling option has been added to erlang:system_flag/2. This option can be used for blocking and unblocking multi-scheduling. For more information see the erlang(3) documentation.

Own Id: OTP-6403

A port program that had been started with the exit_status option and closed one of the pipes used for communication with the emulator caused the emulator to continuously poll for termination of the port program. This only became a problem when the emulator didn't have other things to do and the port program closed a pipe much earlier than it terminated. When the emulator had other things to do, such as running Erlang processes, the emulator polled for termination in between scheduling of processes.

Now the emulator doesn't poll for termination of the port program at all; instead, it waits for the child signal from the terminated port program to arrive and then schedules the Erlang port for termination.

The termination of any port programs have also been optimized. Previously the termination of any port program did always cause a scan of a table of the size equal to maximum number of file descriptors. If the maximum number of file descriptors was large, this scan could be quite expensive. Now the search have been reduced to the set of ports started with the exit_status option.

Note, all of the above only applies to Erlang emulators on Unix platforms.

Own Id: OTP-6412 Aux Id: seq10194

* BEAM: added support for floating-point exceptions on FreeBSD (32-bit x86)

* SMP: made locking procedures work even when native lock operations aren't implemented

* SMP: improved timing accuracy in the timer thread (if enabled)

Own Id: OTP-6424

## Erts 5.5.2.2

### Fixed Bugs and Malfunctions

A bug in the kernel poll implementation could cause the emulator to omit polling for events on file descriptors. The bug was only present when using the kernel poll implementation based on epoll or kqueue. This bug was introduced in erts-5.5.2.

Own Id: OTP-6344 Aux Id: OTP-6222

## Erts 5.5.2.1

### Fixed Bugs and Malfunctions

The run_erl program now acquires its pseudo-ttys using openpty(3), so that it will work on newer Linux distributions that don't have the traditional pseudo-tty devices in the file system. On platforms that don't have openpty(3), run_erl will still search for pseudo-tty devices in the file system.

The run_erl program will now wait using waitpid(3) to prevent the program it spawned to become defunct. run_erl will also terminate after a delay of 5 seconds (to allow any pending output to be written to the log file) if the spawned program terminates even if some child of it still holds stdin and/or stdout open.

Own Id: OTP-6225 Aux Id: seq10500

A bug in ordered_set ETS datatyp caused ets:select (and match) to return faulty results when the table contained process id's from another node.

Own Id: OTP-6338

## Erts 5.5.2

### Fixed Bugs and Malfunctions

erlc: A typo in the help text for '-pa path' was corrected.

Own Id: OTP-6218

Failure in port command/control driver callbacks could crash the non-SMP emulator. This bug was introduced in the 5.5 version of erts.

Own Id: OTP-6224

Erroneous "Input driver gone away without deselecting!" error reports could sometimes occur when a driver instance terminated in the ready_output() callback of the driver. This bug was only present in emulators that used poll(). Note, that this bug was harmless, the only effect it had was the erroneous error report.

Own Id: OTP-6229 Aux Id: OTP-3993, Seq5266, Seq7247, OTP-4307

The emulator could cause a type assertion failure while writing an erl_crash.dump, causing the erl_crash.dump to be terminated and a core dump generated.

Own Id: OTP-6235 Aux Id: seq10444

The registered name of a process is now the last observable resource removed before links and monitors are triggered when a process terminates.

Previously ets tables were removed after the registered name. This could cause problems on the runtime system with SMP support for code that expected that ets tables owned by a specific process had been removed if the name of the process had been removed.

Own Id: OTP-6237

Failure to fork() a new (os) process could cause the emulator to deadlock. This bug affect all emulators with SMP support, and emulators with async thread support on SunOS.

Own Id: OTP-6241 Aux Id: OTP-3906

Fprof traces could become truncated for the SMP emulator. This bug has now been corrected.

Own Id: OTP-6246

The undocumented functions inet:getiflist/0,1 inet:ifget/2,3 and inet:getif/1 were completely broken on Windows. That has been fixed.

Own Id: OTP-6255

Behavior in case of disappeared nodes when using the dist_auto_connect once got changed in R11B-1. The timeouts regarding normal distributed operations is now reverted to the old (pre R11B-1).

Own Id: OTP-6258 Aux Id: OTP-6200, seq10449

The bsl and bsr operators could cause the emulator to crash if given invalid arguments. (Thanks to datacompboy and Per Gustafsson.)

Own Id: OTP-6259

driver_cancel_timer() could under certain circumstances fail to cancel the timer on the runtime system with SMP support.

Own Id: OTP-6261

A call to erlang:system_info(info) could deadlock the runtime system with SMP support.

Own Id: OTP-6268

### Improvements and New Features

Exit signals are now truly asynchronous in the runtime system with SMP support. This simplifies locking in bifs a lot, and makes process termination cheaper.

Own Id: OTP-6160

When tracing on the runtime system with SMP support it can be difficult to know when a trace has been delivered to the tracer. A new built in function erlang:trace_delivered/1 has been introduced in order to make it easier to know when the trace has been delivered. See the erlang(3) man page for more information.

Own Id: OTP-6205 Aux Id: OTP-6269

Kernel poll support can now be combined with SMP support. Currently the following kernel poll versions exist: /dev/poll, epoll, and kqueue. Linux kpoll has been replaced with epoll. Some time in the future there will also be a kernel poll version using Solaris event ports.

The "check io" implementation for unix has been completely rewritten. The current kernel poll implementation reduce the amount of system calls needed compared to the old kernel poll implementation.

When epoll or kqueue is used either poll or select is used as fallback. Previously only poll could be used as fallback. Since select now can be used as fallback, kernel poll support is now also available on newer MacOSX. Note however, when select is used as fallback, the maximum number of file descriptors is limited to FD_SETSIZE.

Kernel poll support is now enabled by default if /dev/poll, epoll, or kqueue is found when building OTP, i.e. you do not have to pass the --enable-kernel-poll argument to configure. As before, kernel poll is disabled by default in the runtime system. In order to enable it, pass the +Ktrue command line argument to erl.

Note: configure will refuse to enable kernel poll support on FreeBSD since kqueue have problems with (at least) pipes on all version of FreeBSD that we have tested.

Own Id: OTP-6222 Aux Id: seq10380

The erl_ddll module and the code in the emulator have been completely rewritten; several bugs were fixed.

Own Id: OTP-6234

The SMP emulator now avoids locking for the following operations (thus making them as fast as in the UP emulator): atom_to_list/1, atom comparison, atom hashing, erlang:apply/3.

Own Id: OTP-6252

There are new BIFs erlang:spawn_monitor/1,3, and the new option monitor for spawn_opt/2,3,4,5.

The observer_backend module has been updated to handle the new BIFs.

Own Id: OTP-6281

## Erts 5.5.1.1

### Improvements and New Features

There is now an option read_packets for UDP sockets that sets the maximum number of UDP packets that will be read for each invocation of the socket driver.

Own Id: OTP-6249 Aux Id: seq10452

## Erts 5.5.1

### Fixed Bugs and Malfunctions

Complex pattern matching of strings would fail in the 64 bits emulator because of a bug in the loader. (Thanks to Igor Goryachev.)

Own Id: OTP-6142

-134217728 div 134217728 and -134217728 rem 134217728 would be calculated incorrectly. abs(-2147483648) could in unlucky circumstances cause a heap overflow, as could size(Binary) when size of the binary was larger than 128Mb.

Own Id: OTP-6154

erlang:display/1 displayed erroneous values for negative integers.

Big integers (both positive and negative) were previously displayed in hexadecimal form while small integers were displayed in decimal form. All integers are now displayed in decimal form.

NOTE: erlang:display/1 should only be used for debugging.

Own Id: OTP-6156

A call to erlang:trace/3 with erroneous flags caused the SMP emulator to deadlock instead of exiting the calling process with badarg.

Own Id: OTP-6175

A bug causing the emulator to hang when exiting a process that is exception traced has been fixed.

Own Id: OTP-6180

ets:rename/1 could deadlock, or crash the SMP emulator when the table wasn't a named table.

ets:next/2, and ets:prev/2 could return erroneous results on the SMP emulator.

Own Id: OTP-6198 Aux Id: seq10392, seq10415

A memory allocation bug could cause the SMP emulator to crash when a process had executed a receive after with a larger timeout than 10 minutes.

Own Id: OTP-6199

The runtime system with SMP support did not slowly adjust its view of time when the system time suddenly changed.

Timeouts could sometimes timeout too early on the runtime system with SMP support.

Own Id: OTP-6202

### Improvements and New Features

The smp runtime system now automatically detects the number of logical processors on MacOSX (darwin) and OpenBSD.

The smp runtime system is now built by default on MacOSX (darwin) on x86.

Own Id: OTP-6119

The -smp command line argument now take the following options: enable, auto, or disable.

Especially the -smpauto argument is useful since it starts the Erlang runtime system with SMP support if it is available and more than one logical processor are detected; otherwise, it starts the Erlang runtime system without SMP support. For more information see the erl(1) man page.

Own Id: OTP-6126

Increased the reduction cost for sending messages in the SMP emulator so it behaves more like the non-SMP emulator.

Own Id: OTP-6196

A port running a dynamically linked-in driver that exits due to the driver being unloaded now exits with exit reason driver_unloaded. Previously the port exited with exit reason -1.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6204

Changed name of the erlang:system_info/1 argument scheduler to scheduler_id. This since the scheduler argument so easily could be mixed up with the schedulers argument (both returning integers).

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6208

The changes below were made by Mikael Pettersson, HiPE.

HiPE runtime system:

Reduce overheads in the HiPE runtime system's BIF glue code.

Fix bug when exceptions are thrown from BEAM to HiPE.

Support SPARC on Linux.

Support x86 on FreeBSD.

Floating-point exceptions:

Reduce overheads in checking results of floating-point operations.

Minor bug fix in SSE2 floating-point exception handling.

Support SSE2 floating-point exceptions on 32-bit x86 machines.

Make FP exceptions work in the SMP runtime system on FreeBSD/x86.

Support floating-point exceptions on SPARCs running Linux.

Runtime system:

Minor scheduler optimisation in the non-SMP runtime system.

Substantial reduction of I/O thread overheads in the SMP runtime system if the separate timer thread is used. (In R11B-1, the separate timer thread is not used.)

Own Id: OTP-6211

## ERTS 5.5

### Fixed Bugs and Malfunctions

Previously unlink/1 and erlang:demonitor/2 behaved completely asynchronous. This had one undesirable effect, though. You could never know when you were guaranteed not to be affected by a link that you had unlinked or a monitor that you had demonitored.

The new behavior of unlink/1 and erlang:demonitor/2 can be viewed as two operations performed atomically. Asynchronously send an unlink signal or a demonitor signal, and ignore any future results of the link or monitor.

NOTE: This change can cause some obscure code to fail which previously did not. For example, the following code might hang:

`Mon = erlang:monitor(process, Pid), %% ... exit(Pid, bang), erlang:demonitor(Mon), receive {'DOWN', Mon , process, Pid, _} -> ok %% We were previously guaranteed to get a down message %% (since we exited the process ourself), so we could %% in this case leave out: %% after 0 -> ok end,`

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-5772

Two bugs fixed: If the environment variable ERL_FLAGS was set, its contents would be appended to the end of the command line even if the command line had an -extra options. Changed to place the options from ERL_FLAGS just before -extra. Also, the -smp and -hybrid flags no longer have any effect if placed after -extra.

Own Id: OTP-6054

### Improvements and New Features

The documentation for writing drivers in the ERTS User's Guide has been expanded and updated.

Own Id: OTP-5192

The andalso and orelse operators are now allowed to be used in guards. That also applies to match specifications.

Own Id: OTP-5894 Aux Id: OTP-5149

There is a new trace match spec function {exception_trace} and a corresponding trace message exception_from that can be used to trace on any exit from a function, both normal function return and exception return. See the documentation for details.

The return_to trace message is now also generated when the execution returns to a function due to catching an exception.

Own Id: OTP-5956

Erlang runtime system with SMP (symmetric multi processing) support.

The runtime system with SMP support is in this release focused on stability and there are a number of steps with optimizations to follow before it will take full advantage of multi processor systems. The released system is however truly multi threaded and you will notice increased performance for many applications already. We recommend that you evaluate your application on the SMP version of the runtime system and wait for some more optimizations before you use it in a real product. You will then discover if there are any problems in your application that needs to be fixed in order for it to work properly in a multi threaded environment. More optimized versions of the runtime system with SMP support will be included in the R11B maintenance releases.

The SMP enabled runtime system will be started if the -smp command line argument is passed to the erl command. In order to make use of more than one processor core, multiple scheduler threads are used. By default, the number of scheduler threads will equal the number of processor cores. The number of scheduler threads can be set with the +S command line argument. For more information see the erl(1) man page.

A runtime system with SMP support is by default built on the following platforms if posix threads, and a gcc compiler of at least version 2.95 is found:

Linux with at least kernel version 2.6 and the Native POSIX Thread Library on x86, x86_64, and 32-bits PowerPC.

Solaris of at least version 8 on 32-bits SPARC-V9.

MacOSX of at least version 10.4 (Darwin 8.0) on 32-bits PowerPC.

The runtime system with SMP support is known not to build on:

Windows.

Linux with kernel versions less than 2.4, or without the Native POSIX Thread Library.

Other hardware platforms than x86, x86_64, 32-bits SPARC-V9 and 32-bits PowerPC.

Windows will be supported in a future release.

The runtime system with SMP support might build on other operating systems in combination with supported hardware. In order to force a build of a runtime system with SMP support, pass the --enable-smp-support command line argument to configure. Note, however, that it is not enough that it builds. The underlying thread library and operating system has to provide SMP support as well. If the thread library does not distribute scheduler threads over multiple processor cores then the runtime system will only seemingly provide SMP support. If the runtime system is not built by default on a specific platform, we have not tested it on that platform.

NOTE: The design of SMP support for drivers is ongoing. There will probably be incompatible driver changes (only affecting drivers run on the runtime system with SMP support) released as patches for R11B.

Potential incompatibility: Previously, specific driver call-backs were always called from the same thread. This is not true in the runtime system with SMP support. Calls to call-backs will be made from different threads, e.g., two consecutive calls to exactly the same call-back can be made from two different threads. This will in most cases not be a problem. All calls to call-backs are synchronized, i.e., only one call-back will be called at a time.

In the future the default behavior will probably be the following: Calls to call-backs will, as now, be made from different threads. Calls to call-backs in the same driver instance will be synchronized. It will probably be possible to configure so that all calls to call-backs in all driver instances of a specific driver type will be synchronized. It may be possible to configure so that all calls to call-backs of a driver instance or a of a specific driver type will be made from the same thread.

Parallelism in the Erlang code executed is a necessity for the Erlang runtime system to be able to take advantage of multi-core or multi-processor hardware. There need to be at least as many Erlang processes runnable as processor cores for the Erlang runtime system to be able to take advantage of all processor cores.

An Erlang runtime system with SMP support with only one Erlang process runnable all the time will almost always be slower than the same Erlang runtime system without SMP support. This is due to thread synchronization overhead.

Known major bottleneck in the Erlang runtime system:

Currently the I/O system uses one "big lock", i.e. only one thread can do I/O at a time (with the exception of async threads and threads created by users own linked-in drivers). This is high on the list of things to optimize. Note, code that does not do I/O can be executed at the same time as one thread does I/O.

Some pitfalls which might cause Erlang programs that work on the non-SMP runtime system to fail on the SMP runtime system:

A newly spawned process will often begin executing immediately. Code that expects that the parent process will be able to execute for a while before the child process begins executing is likely to fail.

High priority processes could previously provide mutual exclusion (bad programming style) by preventing normal and low priority processes from being run. High priority processes cannot be used this way to provide mutual exclusion.

erlang:yield() could be used to provide some kind of temporary mutual exclusion (also bad programming style). erlang:yield() cannot be used to provide any kind of mutual exclusion.

Obscure pitfall, only if a process being traced also sends normal messages to the tracer:
The order between trace messages and normal messages is undefined. I.e. the order between normal messages sent from a tracee to a tracer and the trace messages generated from the same tracee to the same tracer is undefined. The internal order of normal messages and the internal order of trace messages will, of course, be preserved as before.

The kernel poll feature is currently not supported by the runtime system with SMP support. It will probably be supported in a future release.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6006 Aux Id: OTP-6095

Linked-in driver modifications.

Linked-in drivers must be recompiled.

The refc field in the ErlDrvBinary type has been removed. The reference count can be accessed via API functions. For more information see the erl_driver(1) man page.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6095 Aux Id: OTP-6006

## ERTS 5.4.13

### Fixed Bugs and Malfunctions

Large files (more than 2 GBytes) are now handled on Solaris 8.

Own Id: OTP-5849 Aux Id: seq10157

A failing bit syntax construction could fail with the PREVIOUS exception reason that had occurred in the process (instead of with badarg).

Own Id: OTP-5911

When building OTP, the Kernel application was built in both the primary and secondary bootstrap steps, which would cause problems if OTP including its bootstrap is checked into a version control system (such as CVS). (Thanks to Sebastian Strollo.)

Own Id: OTP-5921

binary_to_term(<<131,109,255,255,255,255) and similar expressions used to crash the emulator instead of causing a badarg exception. (Thanks to Matthias Lang.)

Own Id: OTP-5933

erlang:hibernate/3 could sometimes crash the emulator when no heap was needed.

Own Id: OTP-5940

Execution of match specs could under rare circumstances cause the emulator to dump core.

Execution of match specs could cause memory leaks in the hybrid emulator.

Own Id: OTP-5955

A bug in erlang:trace_info/2 when getting info for a function in a deleted module resulting in an emulator crash, has been corrected.

Own Id: OTP-5957

Different (and old) config.guess files in the ERTS and Erl_Interface applications would cause build problems on the new Intel-based iMacs. (Thanks to Sebastion Strollo.)

Own Id: OTP-5967

pthread header and library mismatch on Linux systems (at least some SuSE and Debian) with both NPTL and Linuxthreads libraries installed.

Own Id: OTP-5981

### Improvements and New Features

The driver_set_timer did not change the previous timeout if called a second time. Now it works as specified, changing the timeout.

Own Id: OTP-5942

The undocumented {packet,http} option (for the gen_tcp module) did not not work correctly when there were multiple continuation lines. (Thanks to Per Hedeland.)

Own Id: OTP-5945

The setuid_socket_wrap program was corrected to work for C compilers that treat the char type as unsigned. (Thanks to Magnus Henoch.)

Own Id: OTP-5946

## ERTS 5.4.12

### Fixed Bugs and Malfunctions

Fixed a minor build problem on Windows.

Own Id: OTP-5819 Aux Id: OTP-5382 OTP-5540 OTP-5577

The delay_send option for gen_tcp was broken on Windows.

Own Id: OTP-5822

If there were user-defined variables in the boot script, and their values were not provided using the -boot_var option, the emulator would refuse to start with a confusing error message. Corrected to show a clear, understandable message.

The prim_file module was modified to not depend on the lists module, to make it possible to start the emulator using a user-defined loader. (Thanks to Martin Bjorklund.)

Own Id: OTP-5828 Aux Id: seq10151

### Improvements and New Features

The HiPE compiler identifies more leaf functions, giving slightly faster code.

Corrected problems in HiPE's coalescing register allocating that would cause it to fail when compiling very large functions (e.g. some of parse modules in the Megaco application).

Own Id: OTP-5853

## ERTS 5.4.11

### Fixed Bugs and Malfunctions

Timers could sometimes timeout too early. This bug has now been fixed.

Automatic cancellation of timers created by erlang:send_after(Time,pid(),Msg) and erlang:start_timer(Time,pid(),Msg) has been introduced. Timers created with the receiver specified by a pid, will automatically be cancelled when the receiver exits. For more information see the erlang(3) man page.

In order to be able to maintain a larger amount of timers without increasing the maintenance cost, the internal timer wheel and bif timer table have been enlarged.

Also a number of minor bif timer optimizations have been implemented.

Own Id: OTP-5795 Aux Id: OTP-5090, seq8913, seq10139, OTP-5782

erlang:monitor(process,Pid) hanged if Pid referred to a process on a non-existing node with the same nodename as the nodename of node on which the call was made. This bug has now been fixed.

Own Id: OTP-5827

### Improvements and New Features

By setting Unix environment variables, the priority for the emulator can be lowered when it is writing crash dumps and the time allowed for finishing writing a crash dump can be set to a certain number of seconds. See the documentation for erl in the ERTS application. (Also, a few other previously undocumented environment variables are now documented.)

Own Id: OTP-5818

Documentation improvements:

- documentation for erlang:link/1 corrected

- command line flag -code_path_cache added

- erl command line flags clarifications

- net_kernel(3) clarifications

Own Id: OTP-5847

## ERTS 5.4.10

### Fixed Bugs and Malfunctions

-D_GNU_SOURCE is now always passed on the compile command line on linux. This in order to ensure that all included system headers see _GNU_SOURCE defined.

_GNU_SOURCE is now also defined on linux in configure when looking for features.

Some minor (harmless) configure bugs were also fixed.

Own Id: OTP-5749

Some compiler warnings and Dialyzer warnings were eliminated in the Tools application.

When tracing to a port (which fprof does), there could be fake schedule out/schedule in messages sent for a process that had exited.

Own Id: OTP-5757

### Improvements and New Features

The BIFs iolist_size/1 and iolist_to_binary/1 has been added.

The BIF list_to_existing_atom/1 has been added.

Minor bug fix: The exception reason could be changed to error inside nested try/catch constructs if the erlang:raise/3 BIF was called with an empty stacktrace. (Calling erlang:raise/3 with an empty stacktrace is NOT recommended.)

Minor bugfix: On Windows, file:open/2 will now return the documented error reason {error,eisdir} if the filename refers to a directory (it used to return {error,eacces}).

The message in the documentation for erlang:system_monitor/2, description of busy_dist_port, was corrected.

Own Id: OTP-5709 Aux Id: seq10100

The previously undocumented and UNSUPPORTED zlib module has been updated in an incompatible way and many bugs have been corrected. It is now also documented.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-5715

New socket options priority and tos for platforms that support them (currently only Linux).

Own Id: OTP-5756

Only the emulator is now linked with termcap library in order to decrease library dependencies for other otp programs.

Own Id: OTP-5758

## ERTS 5.4.9.2

### Fixed Bugs and Malfunctions

The native resolver has gotten an control API for extended debugging and soft restart. It is: inet_gethost_native:control(Control)
Control = {debug_level,Level} | soft_restart
Level = integer() in the range 0-4.

Own Id: OTP-5751 Aux Id: EABln25013

## ERTS 5.4.9.1

### Improvements and New Features

On VxWorks, epmd did not handle file descriptors with higher numbers than 63. Also, if epmd should get a file descriptor with a number >= FD_SETSIZE, it will close a the file descriptor and write a message to the log (instead of mysteriously fail); the Erlang node that tried to register will fail with a duplicate_name error (unfortunately, epmd has no way to indicate to the Erlang node why the register attempt failed).

Own Id: OTP-5716 Aux Id: seq10070

## ERTS 5.4.9

### Fixed Bugs and Malfunctions

Timezone data is now initialized better. (was a problem at least on NetBSD 2.0.2) Thanks to Rich Neswold.

Own Id: OTP-5621

The hybrid-heap emulator ('erl -hybrid') is much more stable. We have corrected all known bugs that caused it to dump core while running our test suites.

Own Id: OTP-5634

Fixed rare memory leaks in erlang:demonitor/1 when distributed monitors were removed.

Own Id: OTP-5692

Processes were sometimes unnecessarily garbage collected when terminating. These unnecessary garbage collections have now been eliminated.

Own Id: OTP-5693

### Improvements and New Features

The c:i/0 function will now run in a paged mode if there are more than 100 processes in the system. (Thanks to Ulf Wiger.)

erlang:system_info(process_count) has been optimized and does now return exactly the same value as length(processes()). Previously erlang:system_info(process_count) did not include exiting processes which are included in length(processes()).

The +P flag for erl, which sets the maximum number of processes allowed to exist at the same, no longer accepts values higher than 134217727. (You will still probably run out of memory before you'll be able to reach that limit.)

Own Id: OTP-5645 Aux Id: seq9984

The term-building driver functions driver_output_term() and driver_send_term() have been updated:

The ERL_DRV_FLOAT type has been added.

For the ERL_DRV_BINARY type, the length and offset are now validated against the length of the driver binary.

The ERL_DRV_PID type is now implemented (it was documented, but not implemented).

Own Id: OTP-5674

## ERTS 5.4.8

### Fixed Bugs and Malfunctions

ets:delete/1 now allows other Erlang process to run when a large table is being deleted.

Own Id: OTP-5572

A bug regarding tcp sockets which results in hanging gen_tcp:send/2 has been corrected. To encounter this bug you needed one process that read from a socket, one that wrote more date than the reader read out so the sender got suspended, and then the reader closed the socket. (Reported and diagnosed by Alexey Shchepin.)

Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)

Updated the documentation regarding the second argument to gen_tcp:recv/2, the Length to receive.

Own Id: OTP-5582 Aux Id: seq9839

Erlang/OTP will now build on Mac OS X 10.4 "Tiger" (the problem was that 10.4 has a partially implemented poll() function that can't handle devices). Also, on Mac OS X 10.3 "Panther", Erlang/OTP will now use select() instead of poll() (because poll() on Mac OS X 10.3 is implemented using select()).

Own Id: OTP-5595

A bug in the file driver when opening a file in compressed mode, and the returned allocated pointer from the compressing library was in very high memory (>= 2GB), causing e.g. file:read/2 to return {error,ebadf}, has been corrected.

Own Id: OTP-5618

### Improvements and New Features

The new fun M:F/A construct creates a fun that refers to the latest version of M:F/A. This syntax is meant to replace tuple funs {M,F} which have many problems.

The new type test is_function(Fun,A) (which may be used in guards) test whether Fun is a fun that can be applied with A arguments. (Currently, Fun can also be a tuple fun.)

Own Id: OTP-5584

In the HiPE application, there's a new experimental register allocator (optimistic coalescing), and the linear scan register allocator is now also available on ppc. Plus lots of cleanups.

Minor hybrid heap corrections.

The maximum size of a heap used to be artificially limited so that the size of a heap would fit in 28 bits; that limitation could cause the emulator to terminate in a garbage collection even if there still was available memory. Now the largest heap size for a 32 bit CPU is 1,699,221,830 bytes. (Thanks to Jesper Wilhelmsson.)

Also removed the undocumented +H emulator option.

Own Id: OTP-5596

## ERTS 5.4.7

### Fixed Bugs and Malfunctions

to_erl could close unexpectedly on Linux systems. Also, output from the emulator could be lost. Corrected.

Own Id: OTP-5561

### Improvements and New Features

The cpu_timestamp option for erlang:trace/3 is now also supported on Linux.

Own Id: OTP-5532 Aux Id: seq9813

The last known werl window size/position is now saved correctly when werl is stopped with the window minimized. A problem with the placement not being saved if the emulator is halted or stopped from the JCL menu has also been fixed.

Own Id: OTP-5544 Aux Id: OTP-5522

## ERTS 5.4.6

### Fixed Bugs and Malfunctions

Some math libraries do not always throw floating-point exceptions on errors. In order to be able to use these libraries, floating-point errors are now more thoroughly checked.

Misc floating-point fixes for Linux and MacOSX.

Own Id: OTP-5467

An internal buffer was sometimes not cleared which caused garbage to appear in error messages sent to the error logger.

errno was sometimes clobbered which caused erroneous error reports about poll() errors.

Only emulators on unix platforms were affected by these bugs.

Own Id: OTP-5492

The ethread library now works on OpenBSD.

Own Id: OTP-5515

Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)

Own Id: OTP-5519

### Improvements and New Features

binary_to_term/1 could cause the emulator to crash when given invalid pids or funs.

Own Id: OTP-5484 Aux Id: seq9801

Some more stability problems were fixed in the hybrid-heap emulator.

Own Id: OTP-5489

After werl was closed with the window minimized, it was not possible to restart werl with an open window. A temporary solution has so far been implemented that restores the initial window settings every time werl is started.

Own Id: OTP-5522

## ERTS 5.4.5

### Fixed Bugs and Malfunctions

If a process had node links (created by monitor_node/2), executing process_info(Pid,memory) for that process would crash the emulator.

Own Id: OTP-5420

Minor corrections to the help text printed by erlc -help. The documentation for erlc was also slightly updated.

Own Id: OTP-5428

32-bit words were used for offsets in the garbage collector. This caused the emulator to crash on 64-bit machines when heaps were moved more than 4 GB during garbage collection.

Own Id: OTP-5430

is_boolean(42.5) failed to load if optimization was explicitly turned off.

Own Id: OTP-5448

If there was a call to Module:foo/X from any loaded module, the returned by M:module_info(exports) would always include {foo,X} (even though Module:foo/X if was not defined).

Own Id: OTP-5450 Aux Id: seq9722

### Improvements and New Features

The c option for the +B flag has been introduced which makes it possible to use Ctrl-C (Ctrl-Break on Windows) to interrupt the shell process rather than to invoke the emulator break handler. All new +B options are also supported on Windows (werl) as of now. Furthermore, Ctrl-C on Windows has now been reserved for copying text (what Ctrl-Ins was used for previously). Ctrl-Break should be used for break handling. Lastly, the documentation of the system flags has been updated.

Own Id: OTP-5388

## ERTS 5.4.4

### Fixed Bugs and Malfunctions

The function erlang:float/1 can now be used in match specifications and is recognized by dbg:fun2ms/1 and ets:fun2ms/1. This addition is part of the work to "harmonize" match specification guards with Erlang guards.

Own Id: OTP-5297 Aux Id: OTP-4927

The register/2 BIF would return true even if the second argument was not a pid for living process. Corrected to cause an exception.

Own Id: OTP-5324 Aux Id: seq9698

In the 'bag' type of ets tables, elements having the same key were supposed to be order in insertion order. The would be wrong if a rehash occurred.

Own Id: OTP-5340 Aux Id: seq9704

Linked in drivers in the Crypto and Asn1 applications are now compiled with the -D_THREAD_SAFE and -D_REENTRANT switches on unix when the emulator has thread support enabled.

Linked in drivers on MacOSX are not compiled with the undocumented -lbundle1.o switch anymore. Thanks to Sean Hinde who sent us a patch.

Linked in driver in Crypto, and port programs in SSL, now compiles on OSF1.

Minor makefile improvements in Runtime_Tools.

Own Id: OTP-5346

Fixed a bug in the hybrid heap in distributed send operations.

Own Id: OTP-5361

A BIF erlang:raise/3 has been added. See the manual for details. It is intended for internal system programming only, advanced error handling.

Own Id: OTP-5376 Aux Id: OTP-5257

Mikael Pettersson (HiPE) corrected a few bugs in the emulator that caused problems when compiled with the experimental gcc-4.0.0.

Own Id: OTP-5386

### Improvements and New Features

Minor update of the internal documentation of the epmd protocol.

The listen port of epmd has now been registered at IANA: http://www.iana.org/assignments/port-numbers.

Own Id: OTP-5234

run_erl.c now works on Mac OS X and FreeBSD.

Own Id: OTP-5384

A few bugs were corrected in the HiPE application.

Own Id: OTP-5385

## ERTS 5.4.3

### Fixed Bugs and Malfunctions

Font and color preferences for werl.exe now can be saved even after the first time you run werl.exe. The window position and size is also saved. Patch from James Hague who did all the hard work.

Own Id: OTP-5250

OTP archive libraries, e.g. the erl_interface library, on MacOSX could not be used without first rerunning ranlib on them. This bug has now been fixed.

Own Id: OTP-5274

Bugs in erlang:hash/2 and erlang:phash/2 on 64-bit platforms have been fixed.

Own Id: OTP-5292

### Improvements and New Features

Corrected a crash in the 64-bits emulator.

Corrected a problem in the hybrid heap emulator.

In the chapter about the abstract format in the ERTS User's Guide, updated the last section about how the abstract format is stored in BEAM files.

Own Id: OTP-5262

The maximum number of concurrent threads in the internal ethread thread package has been limited to 2048.

Own Id: OTP-5280

## ERTS 5.4.2.1

### Improvements and New Features

If Erlang/OTP was installed in a short directory name, such as C:\Program\erl5.4.2, the emulator would not start.

Own Id: OTP-5254

## ERTS 5.4.2

### Fixed Bugs and Malfunctions

If one used select/3 and select/1 on a non-fixed ETS table and deleted objects simultaneously, the emulator could crash. Note that the result of such simultaneous operations on tables that are not in a fixed state is still undefined, but the emulator crash is, needless to say, fixed.

Own Id: OTP-5209 Aux Id: seq9198

Arithmetic with big numbers could crash the emulator.

The HiPE native code compiler and run-time code in the emulator has been updated. (Note: Native code is still not supported.)

Eliminated a few bugs that could crash the hybrid emulator (which is not supported).

Own Id: OTP-5233 Aux Id: seq9587

## ERTS 5.4.1

### Fixed Bugs and Malfunctions

The ethread library was unnecessarily rebuilt multiple times during the build process, also a debug version of the library was build during the install phase. These unnecessary builds have now been removed. Note, the content of the installed Erlang/OTP system is not effected at all by this change.

Own Id: OTP-5203

The emulator could fail to clear the memory segment cache. This could potentially cause memory allocation to unnecessarily fail when memory usage was close to its maximum. This bug has now been fixed.

Own Id: OTP-5211

std_alloc (std short for standard) was sometimes called def_alloc (def short for default). std_alloc is now everywhere referred to as std_alloc.

Own Id: OTP-5216

A documentation bug has been corrected in the erts_alloc(3) documentation. It was stated that some of the memory allocators present were by default disabled. This is true for Erlang/OTP R9C, but is not true for Erlang/OTP R10B. In R10B all memory allocators present are enabled by default.

Own Id: OTP-5217

### Improvements and New Features

The emulator now close all open files and sockets immediately after receiving an USR1 signal. This causes the emulator to unregister at epmd as early as possible.

Own Id: OTP-5221 Aux Id: OTP-4985, seq9514

Try/catch support in the emulator slightly updated.

Own Id: OTP-5229