Interesting. I've used semaphores with pthreads (only once -- after that I realised plain old mutexes will do). Like your sleep call, I once brought an entire service to a grinding halt by adding a simple `fsync` call (to fix a recovery failure because once a sequenced message we thought we had written to disk before a crash had actually got lost in the buffer). Understanding things at that level makes any new tech fairly easy to grok.