#include <stdlib.h>
#include <pthread.h>
#include <string.h>

#define MAX_THREADS 10
#define queue_max 10000

void *queue[queue_max];
int counter = 0;
pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;



void *thr (void *in)
{
  while (1)
    {
      void *f = NULL;
      pthread_mutex_lock (&m);
      if (!counter)
	{
	  pthread_mutex_unlock (&m);
	  continue;
	}
      f = queue[--counter];
      pthread_mutex_unlock (&m);
      memset (f, 0, 1024);
      free (f);
    }
}

int main()
{
  pthread_t t[MAX_THREADS];
  int i;

  for (i = 0; i < MAX_THREADS; i++)
      pthread_create (&t[i], NULL, thr, NULL);

  for (i = 0; i < queue_max; i++)
    {
      pthread_mutex_lock (&m);
      queue [i] = malloc (1024);
      counter++;
      pthread_mutex_unlock (&m);
    }

  for (i = 0; i < MAX_THREADS; i++)
      pthread_join (t[i], NULL);
}