Problem with pThread sync issue

Question

I am facing a sync issue with pthread. threadWaitFunction1, is a thread wait function. I expect line no. 247 flag = 1 to be executed only after 243-246 has fini

Answer 1

As stated by Alexey Kukanov, the problem is likely spurious wakeup. your code may be corrected to loop until timeout occurs. Note that I also moved the flag setting to be under the mutex.

static void* threadWaitFunction1(void *timeToWaitPtr)
{
    struct timespec *ptr = (struct timespec*) timeToWaitPtr;
    int ret;

    pthread_mutex_lock(&timerMutex);
    cout << "Setting flag =0 inside threadWaitFunction1\n";
    flag=0;
    cout << "Inside threadWaitFunction\n";
    while (pthread_cond_timedwait(&timerCond, &timerMutex, ptr) != ETIMEDOUT)
        ;
    cout << "Setting flag =1 inside threadWaitFunction1\n";
    flag=1;
    pthread_mutex_unlock(&timerMutex);
}

To be on the safe side, you should check the flag under the same mutex to establish ordering