Question

我有以下测试代码子类化multiprocessing的过程：

import multiprocessing as mp

class TestProcess(mp.Process):
    def __init__(self,name):
        super().__init__()
        self.name = name

    def run(self):
        while True:
            print('{} says "I am alive"'.format(self.name))

if __name__ == "__main__" :

    procs = [TestProcess(i) for i in list('ABC')]

    try:
        for p in procs:
            print('starting {}'.format(p.name))
            p.start()
    except KeyboardInterrupt:
        print('caught interrupt')
    except Exception as e:
        print(str(e))
    finally:
        for p in procs:
            print('stopping {}'.format(p.name))
            p.terminate()

由于某种原因A提前终止而没有发送 ctrl + c 并且进程B和C似乎永远不会运行：

host:~ user$ python process_example.py
    starting A
    starting B
    starting C
    A says "I am alive"
    [... x 16 lines]
    A says "I am alistopping A
    stopping B
    stopping C

如果有人能够解释这一点，我会非常感激。

更新

感谢所有人的迅速回应;我已更新到以下内容：

import time
import multiprocessing as mp

class TestProcess(mp.Process):
    def __init__(self,name):
        super().__init__()
        self.name = name

    def run(self):
        while True:
            print('{} says "I am alive"'.format(self.name))
            time.sleep(1)

if __name__ == "__main__" :

    procs = [TestProcess(i) for i in list('ABC')]

    try:
        for p in procs :
            print('starting {}'.format(p.name))
            p.start()
        for p in procs :
            print('joining {}'.format(p.name))
            p.join()
    except KeyboardInterrupt:
        print('caught interrupt')
    except Exception as e:
        print(str(e))
    finally:
        for p in procs :
            print('stopping {}'.format(p.name))
            p.terminate()

现在我明白了：

host:~ user$ python process_example.py
starting A
starting B
starting C
A says "I am alive"
joining A
B says "I am alive"
C says "I am alive"
A says "I am alive"
B says "I am alive"
C says "I am alive"
A says "I am alive"
B says "I am alive"
C says "I am alive"
A says "I am alive"
B says "I am alive"
C says "I am alive"
A says "I am alive"
B says "I am alive"
C says "I am alive"
B says "I am alive"
A says "I am alive"
C says "I am alive"
^Ccaught interrupt
stopping A
stopping B
stopping C

所以只需加入一个线程吗？

Answer 1

我不清楚你对此的期望是什么。启动进程后，代码立即进入finally:块并显式终止所有进程。所以他们当然会停下来。

至于为什么只有“A”表示它还活着，这可能因平台（OS）而异。您的run()方法只是一个“忙碌循环”，尽可能快地打印。在启动它们之后很快就会杀死这些进程，在你的平台上，操作系统永远不会在你终止它们之前为其他进程安排时间片。

尝试，例如，在启动进程的循环之后粘贴time.sleep(10)。这将延迟杀死进程10秒，这可能足以让B和C在操作系统被杀之前得到一些爱;-)。

请解释一下multiprocess.Process子类的提前终止？

1 个答案: