#! /usr/bin/python

from multiprocessing import Process, Pipe, Queue
from time import sleep

SIZE = 100

def queueChild(q):
    list2D = [[i for i in xrange(j * SIZE, (j * SIZE) + SIZE)] for j in xrange(0,SIZE)]
    q.put(list2D)
    #sleep(.5) # Without this delay `list2D` is modified before it is put on the queue
    list2D[-1][-1] = None


def pipeChild(p):
    list2D = [[i for i in xrange(j * SIZE, (j * SIZE) + SIZE)] for j in xrange(0,SIZE)]
    p.send(list2D)
    list2D[-1][-1] = None


if __name__ == '__main__':
    q = Queue()
    pQueue = Process(target = queueChild, args = (q,))
    pQueue.start(); result = q.get(); pQueue.join();
    print "\nFinal value via Queue None?", (result[-1][-1] is None)

##    # Pipe does not have this problem
##    parent_conn, child_conn = Pipe()
##    pPipe = Process(target = pipeChild, args = (child_conn,))
##    pPipe.start(); result = parent_conn.recv(); pPipe.join();
##    print "\nFinal value via Pipe is None?", (result[-1][-1] is None)

    q.close(); q.join_thread()