Question

我正在研究Python多处理管道。我的目标是两个独立的进程，其中一个进程发送另一个消息五次。我没有运行它的问题，但它只是显示他们的PID，就是这样。这段代码我错了什么？我的环境是Windows 10（64位）和Python 3.6.1（32位）。

import os
import multiprocessing as mp
import time

global sending_end, receiving_end 
sending_end, receiving_end = mp.Pipe()

def sender(sending_end=sending_end):
    print('SND PID: ', os.getpid() )
    for _ in range(5):
        sending_end.send('test')
        time.sleep(1)


class receiver(mp.Process):
    def __init__(self):
        mp.Process.__init__(self)

    def run(self, receiving_end=receiving_end):
        print('REC PID: ', os.getpid() )
        print( receiving_end.recv() )
        time.sleep(1)


if __name__ == '__main__':

    print('MAIN PID: ', os.getpid() )

    s = mp.Process( target = sender, args=(sending_end,) )
    s.start()

    r = receiver()
    r.start()     

    mp.freeze_support()

Answer 1

您似乎忘记调用继承run()类（PARENT）的receiver类（CHILD）的multiprocessing.Process方法。

由于未明确调用run()，因此调用了父run()方法，并且它没有您的接收值打印代码。因此，它感觉代码没有运行。

还有一些事情：

两个管道都需要在关闭文件时关闭。
需要调用子类run()方法，直到发送进程处于活动状态。

请检查以下代码，并注明以上几点。

<强>代码：

import os
import multiprocessing as mp
import time

global sending_end, receiving_end
sending_end, receiving_end = mp.Pipe()


def sender(sending_end=sending_end):
    print('SND PID: ', os.getpid() )
    for i in range(5):
        sending_end.send('test_' + str(i) )
        time.sleep(1)
    print "Done from sender"
    #Closing sending pipe
    sending_end.close()


class receiver(mp.Process):
    def __init__(self):
        mp.Process.__init__(self)

    def run(self, receiving_end=receiving_end):
        print('REC PID: ', os.getpid() )
        print( "Dinesh - ",receiving_end.recv() )
        time.sleep(1)


if __name__ == '__main__':
    import sys
    print('MAIN PID: ', os.getpid() )

    s = mp.Process( target = sender, args=(sending_end,) )
    s.start()

    r = receiver()
    r.start()

    while True:
        #Checking sending process is alive or not
        if not s.is_alive():
            print "Sending process is done. Exiting"
            #Closing receiving end pipe
            receiving_end.close()
            #Closing receving process
            r.terminate()
            sys.exit()
        time.sleep(0.1)
        #Explicitly calling run method
        r.run()

    mp.freeze_support()

<强>输出：

('MAIN PID: ', 16400)
('REC PID: ', 16400)
('REC PID: ', 12544)
('SND PID: ', 17744)
('Dinesh - ', 'test_0')
('REC PID: ', 16400)
('Dinesh - ', 'test_1')
('REC PID: ', 16400)
('Dinesh - ', 'test_2')
('REC PID: ', 16400)
('Dinesh - ', 'test_3')
('REC PID: ', 16400)
('Dinesh - ', 'test_4')
Done from sender
Sending process is done. Exiting

我不明白为什么这段代码不起作用（multiprocessing.Pipe）

1 个答案: