Containers
Intel® oneAPI Threading Building Blocks (oneTBB) 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 oneTBB 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.
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.