pthread_cond_timedwait returning immediately

Question

I\'m having a strange problem. I have the following code:

    dbg(\"condwait: timeout = %d, %d\\n\", 
        abs_timeout->tv_sec, abs_timeout->tv_nsec);
          


        

Answer 1

The condition variable can spuriously unblock. You need to check it in a loop and check the condition each time through. You'll probably need to update the timeout value too.

I found some documentation for pthread_cond_timedwait here.

When using condition variables there is always a Boolean predicate involving shared variables associated with each condition wait that is true if the thread should proceed. Spurious wakeups from the pthread_cond_timedwait() or pthread_cond_wait() functions may occur. Since the return from pthread_cond_timedwait() or pthread_cond_wait() does not imply anything about the value of this predicate, the predicate should be re-evaluated upon such return.