pthread_cond_timedwait()

Question

void wait(int timeInMs)
{
    struct timespec timeToWait;
    timeToWait.tv_sec = 5;
    timeToWait.tv_nsec = timeInMs*1000;

    int rt;

    pthread_mutex_lock(&am         


        

Answer 1

Using any variant of sleep, the behavior is not guaranteed. All the threads can also sleep since the kernel is not aware of the different threads.

A safer and cleaner solution to use is pthread_cond_timedwait. You used the API incorrectly. Here is a better example:

pthread_mutex_t fakeMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t fakeCond = PTHREAD_COND_INITIALIZER;

void mywait(int timeInMs)
{
    struct timespec timeToWait;
    struct timeval now;
    int rt;

    gettimeofday(&now,NULL);


    timeToWait.tv_sec = now.tv_sec+5;
    timeToWait.tv_nsec = (now.tv_usec+1000UL*timeInMs)*1000UL;

    pthread_mutex_lock(&fakeMutex);
    rt = pthread_cond_timedwait(&fakeCond, &fakeMutex, &timeToWait);
    pthread_mutex_unlock(&fakeMutex);
    printf("\nDone\n");
}

void* fun(void* arg)
{
    printf("\nIn thread\n");
    mywait(1000);
}

int main()
{
    pthread_t thread;
    void *ret;

    pthread_create(&thread, NULL, fun, NULL);
    pthread_join(thread,&ret);
}

You need to specify how much time to wait from current time. Since you were only telling 5 sec and some nano-seconds it found that the time had already passed and did not wait...Please let me know if any more doubts.