loop in pthread_cond_broadcast

Tue May 1 11:48:00 GMT 2001

Below is a sample program that illustrates a loop in pthread_cond_broadcast()
when called the second time. CPU utilization goes to 100% and the function
never returns.
Thanks, Greg
gsmith@GREG ~
$ cat ptbarf.c
#include <stdio.h>
#include <pthread.h>
void *baby();
pthread_cond_t cond;
pthread_mutex_t lock;
pthread_attr_t attr;
pthread_t tid;
int main ()
{
int i;
 pthread_cond_init(&cond, NULL);
 pthread_attr_init(&attr);
 pthread_mutex_init(&lock, NULL);
 pthread_mutex_lock(&lock);
 pthread_create(&tid, &attr, baby, NULL);
 for (i=0; i<10; i++)
 { sleep(1);
 printf("before cond wait\n");
 pthread_cond_wait(&cond, &lock);
 printf("after cond wait\n");
 }
 pthread_mutex_unlock(&lock);
}
void *baby()
{
 while (1)
 { sleep(2);
 pthread_mutex_lock(&lock);
 printf("before cond broadcast\n");
 pthread_cond_broadcast(&cond);
 printf("after cond broadcast\n");
 pthread_mutex_unlock(&lock);
 }
}
gsmith@GREG ~
$ gcc -o ptbarf ptbarf.c
gsmith@GREG ~
$ ./ptbarf
before cond wait
before cond broadcast
after cond broadcast
after cond wait
before cond wait
before cond broadcast
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