concurrent-extra package offers among other things the following
selection of synchronisation primitives:
Broadcast: Wake multiple threads by broadcasting a value.
Event: Wake multiple threads by signalling an event.
Lock: Enforce exclusive access to a resource. Also known as a binary semaphore or mutex. The package additionally provides an alternative that works in the
RLock: A lock which can be acquired multiple times by the same thread. Also known as a reentrant mutex.
ReadWriteLock: Multiple-reader, single-writer locks. Used to protect shared resources which may be concurrently read, but only sequentially written.
ReadWriteVar: Concurrent read, sequential write variables.
Please consult the API documentation of the individual modules for more detailed information.