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Top Forums Programming How to sleep and wake a thread??? Post 302582627 by DreamWarrior on Friday 16th of December 2011 02:59:14 PM
Old 12-16-2011
Quote:
Originally Posted by jim mcnamara
As John said above, you probably want your thread to block not sleep. Calls like sleep send SIGALRM to the calling process, not just the thread. This means that you have to set up signal handling for the thread in question, and have all the other threads ignore
SIGALRM (example only, there are other signals)

Using a condition wait or a mutex wait is much more efficient.
sleep doesn't send SIGALRM.

At any rate, pause will work, I've seen people do:

Code:
for ( ; ; ) sleep(UINT_MAX);

And then, as mentioned, pthread_kill can wake it provided the thread hasn't blocked the signal.

Also, as mentioned, there is no way for another thread to cause someone to "go to sleep".

For your edification, this seems like a simple producer-consumer model, and that's usually handled with condition variables. See: pthread_cond_init, pthread_cond_wait, and pthread_cond_signal.
 

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pthread_cond_signal(3C) 												   pthread_cond_signal(3C)

NAME
pthread_cond_signal, pthread_cond_broadcast - signal or broadcast a condition SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ] #include <pthread.h> int pthread_cond_signal(pthread_cond_t *cond); int pthread_cond_broadcast(pthread_cond_t *cond); These two functions are used to unblock threads blocked on a condition variable. The pthread_cond_signal() call unblocks at least one of the threads that are blocked on the specified condition variable cond (if any threads are blocked on cond). The pthread_cond_broadcast() call unblocks all threads currently blocked on the specified condition variable cond. If more than one thread is blocked on a condition variable, the scheduling policy determines the order in which threads are unblocked. When each thread unblocked as a result of a pthread_cond_signal() or pthread_cond_broadcast() returns from its call to pthread_cond_wait() or pthread_cond_timedwait(), the thread owns the mutex with which it called pthread_cond_wait() or pthread_cond_timedwait(). The thread(s) that are unblocked contend for the mutex according to the scheduling policy (if applicable), and as if each had called pthread_mutex_lock(). The pthread_cond_signal() or pthread_cond_broadcast() functions may be called by a thread whether or not it currently owns the mutex that threads calling pthread_cond_wait() or pthread_cond_timedwait() have associated with the condition variable during their waits; however, if predictable scheduling behavior is required, then that mutex is locked by the thread calling pthread_cond_signal() or pthread_cond_broad- cast(). The pthread_cond_signal() and pthread_cond_broadcast() functions have no effect if there are no threads currently blocked on cond. If successful, the pthread_cond_signal() and pthread_cond_broadcast() functions return 0. Otherwise, an error number is returned to indi- cate the error. The pthread_cond_signal() and pthread_cond_broadcast() function may fail if: EINVAL The value cond does not refer to an initialized condition variable. See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ pthread_cond_init(3C), pthread_cond_wait(3C), pthread_cond_timedwait(3C), attributes(5), condition(5), standards(5) 23 Mar 2005 pthread_cond_signal(3C)
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