Thread: Trouble with pthread_create and pthread_join

I have these two functions:

Code:

void make_threads(pthread_t *threads, int num_threads, void* (*func)(void *))
{
	int i, *id;

	if((threads = (pthread_t *) calloc(num_threads, sizeof(pthread_t))) == NULL)
	{
		perror("make_threads calloc");
		exit(0);
	}
	
	for(i = 0; i < num_threads; i++)
	{
		if((id = (int *) calloc(1, sizeof(int))) == NULL)
		{
			perror("make_threads id calloc");
			exit(0);
		}		
		
		*id = i; // pointer needed because if I just passed address of i
			// all threads would have the same id address, hence
			// same id		

		if(pthread_create(&threads[i], NULL, func, (void *) id) != 0)
		{
			perror("make_threads pthread_create");	
			exit(0);
		}
	}
}

void join_threads(pthread_t *threads, int num_threads)
{
	int i, *ret_val;
	
	if((ret_val = (int *) calloc(num_threads, sizeof(int))) == NULL)
	{
		perror("join_threads calloc");
		exit(0);
	}

	printf("before loop in join_threads\n");
	for(i = 0; i < num_threads; i++)
		if(pthread_join(threads[i], (void **) (&(ret_val))) != 0)
		{
			perror("join_threads pthread_join");
			exit(0);
		}
	printf("out of join_threads\n");
		
}

and I call them as follows:

Code:

	pthread_t *producers, *qsort_consumers, *bsort_consumers;

	make_threads(producers, num_producers, &producer);
	make_threads(qsort_consumers, num_consumers, &qsort_consumer);
	make_threads(bsort_consumers, num_consumers, &bsort_consumer);
	printf("hello 1\n");
	join_threads(producers, num_producers);
	printf("hello 2\n");
	join_threads(qsort_consumers, num_consumers);
	join_threads(bsort_consumers, num_consumers);
	printf("hello 2\n");

The problem is that the program always dumps core and never prints "hello 2" or "hello 3". It also only prints "before loop in join_threads" only once and never prints "out of join_threads". What's wrong my join_threads function?

Thanks, that's what I was just about thinking about doing.