Python多处理退出优雅地如何? [英] Python Multiprocessing Exit Elegantly How?

问题描述

import multiprocessing
import time

class testM(multiprocessing.Process):

    def __init__(self):
        multiprocessing.Process.__init__(self)
        self.exit = False

    def run(self):
        while not self.exit:
            pass
        print "You exited!"
        return

    def shutdown(self):
        self.exit = True
        print "SHUTDOWN initiated"

    def dostuff(self):
        print "haha", self.exit


a = testM()
a.start()
time.sleep(3)
a.shutdown()
time.sleep(3)
print a.is_alive()
a.dostuff()
exit()

我只是想知道上面的代码为什么并没有真正显示您退出了".我究竟做错了什么?如果是这样，有人可以为我指出正确退出的正确方法吗? (我不是指process.terminate或kill)

I am just wondering how come the code above doesn't really print "you exited". What am I doing wrong? if so, may someone point me out the correct way to exit gracefully? (I am not referring to process.terminate or kill)

推荐答案

之所以没有看到这种情况，是因为您没有与子流程进行通信.您正在尝试使用局部变量(对于父进程而言是局部变量)向子进程发出信号，告知它应该关闭.

The reason you are not seeing this happen is because you are not communicating with the subprocess. You are trying to use a local variable (local to the parent process) to signal to the child that it should shutdown.

看看有关同步化基元的信息.您需要设置在两个过程中都可以引用的某种信号.一旦有了这个，您应该能够在父进程中轻按开关，并等待孩子死亡.

Take a look at the information on synchonization primatives. You need to setup a signal of some sort that can be referenced in both processes. Once you have this you should be able to flick the switch in the parent process and wait for the child to die.

尝试以下代码:

import multiprocessing
import time

class MyProcess(multiprocessing.Process):

    def __init__(self, ):
        multiprocessing.Process.__init__(self)
        self.exit = multiprocessing.Event()

    def run(self):
        while not self.exit.is_set():
            pass
        print "You exited!"

    def shutdown(self):
        print "Shutdown initiated"
        self.exit.set()


if __name__ == "__main__":
    process = MyProcess()
    process.start()
    print "Waiting for a while"
    time.sleep(3)
    process.shutdown()
    time.sleep(3)
    print "Child process state: %d" % process.is_alive()

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