#! /usr/bin/python

# Script demonstrating how modifying an object straight after en-queueing it
# can result in the modified object being added to the queue (only affects
# multiprocessing.Queue and inheriting multiprocessing.JoinableQueue).

from multiprocessing import Process
from multiprocessing.queues import SimpleQueue, Queue, JoinableQueue
from time import sleep

def queueChild(q):
    l = list(xrange(10000))
    q.put(l)
    #sleep(.5) # With this delay both queue types behave the same
    l[-1] = None


if __name__ == '__main__':

    for queueClass in (SimpleQueue, Queue, JoinableQueue):
        q = queueClass()
        p = Process(target = queueChild, args = (q,))
        p.start()
        result = q.get()
        p.join()
        print "\n", str(queueClass), "\nFinal value in queue:", result[-1]