Question

from multiprocessing import Process
from threading import Thread

def main():

    thread1 = myclass(varA)   #subclassed threading.Thread
    thread1.daemon = False
    thread1.start()

    thread2 = Thread(target=myfunc)
    thread2.daemon = False
    thread2.start()

    while True:
        time.sleep(1)


if __name__ == "__main__":

    SUBPROCESS = Process(target=main)
    SUBPROCESS.daemon = False
    SUBPROCESS.start()

为什么脚本会死掉，除非我添加一会儿True：睡眠在main（）中？（线程1和线程2都具有永远运行的功能） daemon = False是否应该保持活动状态（子进程和该子进程中的子线程），即使父进程已结束也是如此？

EDIT1（工作代码）（先看一下方法A或方法B的注释，运行时注释其中的一部分）：

from multiprocessing import Process
from threading import Thread
import time


varA = "XYZ"

class myclass(Thread):

    def __init__(self, varA):
        Thread.__init__(self)
        self.varA = varA

    def run(self):
        while True:
            print("myClass prints %s" %self.varA)


def myfunc():
    while True:
        print("myfunc prints")



def main():

    thread1 = myclass(varA)   #subclassed threading.Thread
    thread1.daemon = False
    thread1.start()

    thread2 = Thread(target=myfunc)
    thread2.daemon = False
    thread2.start()


if __name__ == "__main__":

    #METHOD A: Running as subprocess = subthreads in that subprocess will die
    SUBPROCESS = Process(target=main)
    SUBPROCESS.daemon = False
    SUBPROCESS.start()


    #METHOD B: Running as main process = subthreads in that subprocess wont die as desired
    thread1 = myclass(varA)   #subclassed threading.Thread
    thread1.daemon = False
    thread1.start()

    thread2 = Thread(target=myfunc)
    thread2.daemon = False
    thread2.start()

Answer 1

这是Python issue 18966；在关闭之前，多处理进程没有join非守护进程线程。该行为已在Python 3.7.0中更改，因此现在可以join处理其非守护进程线程。

守护程序行为多处理多线程

1 个答案: