why does my print function (in multiprocessing) print nothing?

问题

why does my print function (in python multiprocess) print nothing?

from multiprocessing import Process, Queue
import os, time, random


def write(q):
    print('Process to write: %s' % os.getpid())
    for value in ['A', 'B', 'C']:
        print('Put %s to queue...' % value)
        q.put(value)
        time.sleep(random.random())


def read(q):
    print('Process to read: %s' % os.getpid())
    while True:
        value = q.get(True)
        print('Get %s from queue.' % value)

if __name__=='__main__':

    q = Queue()
    pw = Process(target=write, args=(q,))
    pr = Process(target=read, args=(q,))

    pw.start()
    print('start')

    pr.start()

    pw.join()

    pr.terminate()
    print('end')

I run it on spyder (windows 10 system).

My result on IPython console of Spyder:

runfile('C:/Users/Dust/Desktop/programs/crawl/test.py', wdir='C:/Users/Dust/Desktop/programs/crawl')
start
end

Result on Python console of Spyder:

>>> runfile('C:/Users/Dust/Desktop/programs/crawl/test.py', wdir='C:/Users/Dust/Desktop/programs/crawl')
start
Process to write: 12824
Put A to queue...
Put B to queue...
Put C to queue...
end

It is really weird. The results are different, but both are not what I want.

Could anyone help me find where is the problem in my program. Thanks a lot

来源：https://stackoverflow.com/questions/45587101/why-does-my-print-function-in-multiprocessing-print-nothing