Michael Glassford <glassfordm <at> hotmail.com> writes:
How does it know when to release all the threads? Do you mean that you would "register" ahead of time which threads are supposed to wait, and it releases them all when they have all waited on the barrier? What would happen if an "unregistered" thread tried to wait on the barrier?
Yes, you could use the group for registration - have a set of threads which are all in the group, and each thread in the group blocks on the barrier unless it is the last thread of the the group to reach the barrier, in which case it releases all the other threads. This would have to be a layer above pthread_barrier, I guess, and I don't think the pthread barrier would actually be used to implement it... Is there any high performance- or correctness- oriented magic in the platform's barrier implementation? If a thread that was not part of the thread group waited on the barrier, you could either throw an exception, or simply allow it to also wait until the rest of the groups threads had entered. I'm not sure how this could be worked into the syntax, though...