2012/8/15 andrea crotti <[email protected]>:
> I'm having a few problems with PUSH/PULL and multiple processes, so I
> tried to make a simple example to understand what's going on, but
> still is not clear..
>
> In the following example I would expect to receive two tasks from the
> two different processes and then quit, instead it receives the first
> one and then hangs.. Why is that? (Also using ipc instead of tcp
> produces the same behaviour).
>
> Are there issues with multiprocessing for example that I should be
> aware of?
>
> import zmq
> from time import sleep
> from multiprocessing import Process
>
> # TODO: this only works on Linux
> PORT = 'tcp://127.0.0.1:4444'
>
>
> def start_send():
> ctx = zmq.Context()
> task_sender = ctx.socket(zmq.PUSH)
> task_sender.bind(PORT)
> task_sender.send('hello')
> task_sender.send('world')
>
>
> def start_receive():
> ctx = zmq.Context()
> task_recv = ctx.socket(zmq.PULL)
> task_recv.connect(PORT)
> msg = task_recv.recv()
> print(msg)
>
>
> if __name__ == '__main__':
> p1 = Process(target=start_send)
> p2 = Process(target=start_receive)
> p3 = Process(target=start_receive)
> p1.start()
> p2.start()
> p3.start()
I just discovered that adding a sleep between the two send makes it
actually work, so in the "normal" case one message just gets lost, but
why??
task_sender.send('hello')
sleep(1)
task_sender.send('world')
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