In pthread, how to reliably pass signal to another thread?

Question

I\'m trying to write a simple thread pool program in pthread. However, it seems that pthread_cond_signal doesn\'t block, which creates a problem. For example, let\'

Answer 1

Use a synchronization variable.

In main:

pthread_mutex_lock(&my_cond_m);
while (!flag) {
    pthread_cond_wait(&my_cond, &my_cond_m);
}
pthread_mutex_unlock(&my_cond_m);

In the thread:

pthread_mutex_lock(&my_cond_m);
flag = 1;
pthread_cond_broadcast(&my_cond);
pthread_mutex_unlock(&my_cond_m);

For a producer-consumer problem, this would be the consumer sleeping when the buffer is empty, and the producer sleeping when it is full. Remember to acquire the lock before accessing the global variable.