# Containers

Intel® Threading Building Blocks (Intel® TBB) provides highly concurrent container classes. These containers can be used with raw Windows* OS or Linux* OS threads, or in conjunction with task-based programming.

A concurrent container allows multiple threads to concurrently access and update items in the container. Typical C++ STL containers do not permit concurrent update; attempts to modify them concurrently often result in corrupting the container. STL containers can be wrapped in a mutex to make them safe for concurrent access, by letting only one thread operate on the container at a time, but that approach eliminates concurrency, thus restricting parallel speedup.

Containers provided by Intel® TBB offer a much higher level of concurrency, via one or both of the following methods:

- Fine-grained locking: Multiple threads operate on the container by locking only those portions they really need to lock. As long as different threads access different portions, they can proceed concurrently.

- Lock-free techniques: Different threads account and correct for the effects of other interfering threads.

Notice that highly-concurrent containers come at a cost. They typically have higher overheads than regular STL containers. Operations on highly-concurrent containers may take longer than for STL containers. Therefore, use highly-concurrent containers when the speedup from the additional concurrency that they enable outweighs their slower sequential performance.

### Caution

As with most objects in C++, the constructor or destructor of a container object must not be invoked concurrently with another operation on the same object. Otherwise the resulting race may cause the operation to be executed on an undefined object.

Parent topic: Intel® Threading Building Blocks (Intel® TBB) User Guide

- concurrent_hash_map
- concurrent_vector
- Concurrent Queue Classes
- Summary of Containers

## See Also

Task Based Programming