1

Is it possible to use multiprocessing.Event to implement a synchronization barrier for pool of processes? I am using Python 2.7. But it looks like the Event is not shared between processes. Is something wrong with my code?

def test_func(event):
    event.wait()
    return datetime.datetime.now()

def log_result(result):
    result_list.append(result)

if __name__ == '__main__':
    pool_size=10
    pool = multiprocessing.Pool(processes=pool_size)
    event = multiprocessing.Manager().Event()
    for _ in xrange(pool_size):
        pool.apply_async(test_func, args=(event,), callback=log_result)
    pool.close()
    pool.join()   
    time.sleep(5)
    event.set()
leon01
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1 Answers1

3

You have dead-lock: pool.join() waits for started processes and all processes wait on event.wait(). Sedd pool join:

join()

Wait for the worker processes to exit

Basically you have to move "pool.join()" after "event.set()" and all should be OK.

ddzialak
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