Re: Problem with pthread_cond_timedwait().

[Ross Johnson <rpj at ise dot canberra dot edu dot au>]

Hi all,

This is to let people know that Alexander Terekhov has located the 
problem, with a suspicion of possibly a deeper problem elsewhere 
(which will be investigated), and provided a fix which is now in the 
CVS repository.

The latest CVS tree has passed both the test suite and the test 
program used to illustrate the bug.

A new snapshot will be produced soon.

Regards.
Ross

Nir Nizry wrote:
> Hello All,
>
> I have a problem with pthread_cond_timedwait().
> I have a system with 5 threads that in their main loop wait with a timeout
> (timedwait) on a condition variable to be set.
> what I get is, that sometimes a thread enters the pthread_cond_timedwait()
> function, and doesn't come out, even if the timeout time arrives. after this
> happens, the other threads get stuck in the mutex lock before entering the
> pthread_cond_timedwait() as if the mutex is already locked.
>
> I suspect that somehow either the pthread_cond_timedwait() function does not
> release the mutex or does not return when the timeout occurs.
>
> does someone have an idea' or know of such an incident (or maybe a bug in
> pthread)??
>
> Thanks.
>
> Nir.
>
> I added the code fraction where it get stucked (this is the ONLY place in
> the code where the messageMutex is locked):
>
>
> pthread_mutex_lock(messageMutex);
>
> waitResult = 0;
> while( m_theGeneralQueue->isEmpty() && !shouldStopThreadGlobalLoop &&
> (waitResult != ETIMEDOUT))
> 	waitResult = pthread_cond_timedwait(newMessageEvent, messageMutex,
> &timeout);
>
> pthread_mutex_unlock(messageMutex);
>
>
> -----------------------------------------
>
> mailto:nir.nizry@bluesoft-inc.com
>
> -----------------------------------------