'''<u>concurrent_hash_map</u>''' : A container class that supports hashing in parallel. The generated keys are not ordered and there will always be at least 1 element for a key. Defined within "'''tbb/concurrent_hash_map.h'''"  '''quotes''': ''Intel Threaded Building Blocks book.'' Highly concurrent containers are very important because Standard Template Library(STL) containers generally are not concurrency-friendly, and attempts to modifythem concurrently can easily corrupt the containers.