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    <p>Your barrier implementation does not work, at least not if the barrier will be used more than once. Consider this case:</p> <ol> <li><code>NUM_OF_THREADS-1</code> threads are waiting at the barrier, spinning.</li> <li>Last thread arrives and passes through the barrier.</li> <li>Last thread exits barrier, continues processing, finishes its next task, and reenters the barrier wait.</li> <li>Only now do the other waiting threads get scheduled, and they can't exit the barrier because the counter was incremented again. Deadlock.</li> </ol> <p>In addition, one often-overlooked but nasty issue to deal with using dynamically allocated barriers is destroying/freeing them. You'd like any one of the threads to be able to perform the destroy/free after the barrier wait returns as long as you know nobody will be trying to wait on it again, but this requires making sure <strong>all waiters</strong> have finished touching memory in the barrier object before <strong>any waiters</strong> wake up - not an easy problem to solve. See my past questions on implementing barriers...</p> <p><a href="https://stackoverflow.com/questions/5886614/how-can-barriers-be-destroyable-as-soon-as-pthread-barrier-wait-returns">How can barriers be destroyable as soon as pthread_barrier_wait returns?</a></p> <p><a href="https://stackoverflow.com/questions/6935769/can-a-correct-fail-safe-process-shared-barrier-be-implemented-on-linux">Can a correct fail-safe process-shared barrier be implemented on Linux?</a></p> <p>And unless you know you have a special-case where none of the difficult problems apply, don't try implementing your own for an application.</p>
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    1. POIs this approach of barriers right?
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    1. POIs this approach of barriers right?
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    1. COVery good observation! Thanks for such a good answer.
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    2. COI actually invented it after in my program I had a piece of code sandwitched b/w two pthread_barrier_waits, so I replaced the first one with my_barrier. What do you think, is it valid for such use or also not valid there?
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    3. COYours will probably work if the barrier is only ever used once, and never destroyed/never destroyable. But it's going to be damn slow when a large number of threads go into a loop spinning on the barrier counter rather than sleeping...
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