On Tue, May 30, 2006 at 07:43:01PM -0700, Luo Kai wrote:
> See the following code:
>
> ------------test.c--------
> #include <sys/types.h>
> #include <unistd.h>
> #include <pthread.h>
> #include <stdio.h>
> #include <sys/resource.h>
>
> pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
> pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
>
> void *func(void *a)
> {
> pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
No. Do not do this. Bad idea. You don't want asynchronous cancellation if
you are calling any non-async-cancel-safe function. pthread_mutex_lock()
is a non-async-cancel-safe function. So is pthread_cond_wait(). In fact,
about the only async-cancel-safe function is pthread_setcanceltype().
> pthread_mutex_lock(&mutex);
> pthread_cond_wait(&cond, &mutex);
> pthread_mutex_unlock(&mutex);
> return NULL;
> }
You need to have a pthread_cleanup_push(pthread_mutex_unlock, &mutex) before
the cond_wait:
pthread_mutex_lock(&mutex);
pthread_cleanup_push(pthread_mutex_unlock, &mutex)
pthread_cond_wait(&cond, &mutex);
pthread_cleanup_pop(1); /* unlock the mutex */
return (NULL);
}
> int main()
> {
> int ii;
> pthread_t tid[3];
> pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
Again, you *really* don't want to do this.
Cheers,
- jonathan
--
Jonathan Adams, Solaris Kernel Development
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