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mcstafford-git/multiproc+vars.py

Created March 6, 2018 23:19
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  1. mcstafford-git created this gist Mar 6, 2018.
    45 changes: 45 additions & 0 deletions multiproc+vars.py
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,45 @@
    # variable scope, lifetime

    # modified from stackoverflow https://goo.gl/Gy5Ai7
    import multiprocessing
    import os


    def hey(pid, message):
    global i
    global queue
    denominator = None
    try:
    denominator = queue.qsize()
    except NameError:
    pass
    print(
    '{}:{}/{}'.format(pid, i, denominator),
    message,
    )
    i += 1


    def worker_main(queue):
    hey(os.getpid(), 'init')
    while True:
    item = queue.get(True)
    hey(os.getpid(), item)


    i = 0
    hey(os.getpid(), 'BEFORE')
    queue = multiprocessing.Queue()
    pool = multiprocessing.Pool(processes=3, initializer=worker_main, initargs=(queue, ))

    for i in range(5):
    queue.put('hello')
    queue.put('world')

    hey(os.getpid(), 'DURING')

    while queue.qsize():
    pass

    hey(os.getpid(), 'AFTER')
    #