I was thinking of methods like these, for example:
def close(self): self.put(sentinel) def __iter__(self): while True: item = self.get() if item is sentinel: break yield item raise StopIteration
That would not be thread-safe because your sentinel is only seen once by a single lucky consumer, other listeners who called iter() will still execute self.get() and block forever. The solution I found is to put the sentinel back in the queue so that other consumers will see it (this use StopIteration as the sentinel): def _iterqueue(queue): # Turn a either a threading.Queue or a multiprocessing.queues.SimpleQueue # into an thread-safe iterator which will exhaust when StopIteration is # put into it. while 1: item = queue.get() if item is StopIteration: # Re-broadcast, in case there is another listener blocking on # queue.get(). That listener will receive StopIteration and # re-broadcast to the next one in line. queue.put(StopIteration) break else: yield item I agree, however, that this should be left out of the stdlib API. -- // aht http://blog.onideas.ws