pthread_cond_wait with multiple mutex variables

["Bharath Ramesh" <bramesh at vt dot edu>]

I am using a benchmark which is associating multiple mutex variables with a
single condition variable to achieve a very particular functionality like a
barrier. The control flow is that there are more than one worker thread
working on their own individual work queue. Each thread is waiting on the
same condition variable, but use a thread specific mutex variable with the
condition wait. The event handler thread queues work for the set of worker
threads and broadcast on the common condition variable. When the worker
threads come out of the wait they check their queue for new work, if empty
they wait on the condition variable again. The benchmark works predictably
on each run, but I believe it is violating what the man page states on how
condition wait works. Quoting from the man page:

 "The effect of using more than one mutex for concurrent
pthread_cond_timedwait() or pthread_cond_wait() operations on the same
condition variable is undefined; that is, a condition variable becomes bound
to a unique mutex when a thread waits on the condition variable, and this
(dynamic) binding shall end when the wait returns."

I am wondering if the behavior of the benchmark is correct.

Regards,

Bharath

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