func: static int spawn_thread(void)
  
  {
  
      pthread_attr_t attr;
  
      int ret;
  
  
  
      cur_threads++;
  
      idle_threads++;
  
  
  
      pthread_attr_init(&attr);
  
      pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  
      ret = pthread_create(&thread_id, &attr, aio_thread, NULL);
  
      pthread_attr_destroy(&attr);
  
  
  
      return ret;
  
  }
  