python 线程：当多个线程之一失败时退出程序

Question

I would like to find a way to have a script exit when one of the threads fail. I have experimented with _thread.interrupt_main() and daemon = True as follow:

import threading
import time
import _thread


def run1(x):
    while True:
        time.sleep(1)
        print(x)


def run_and_stop(x):
    i = 0
    while True:
        time.sleep(1)
        print(x)
        i += 1
        if i == 5:
            _thread.interrupt_main()


t1 = threading.Thread(target = run1, args = ('a', ), daemon = True)
t2 = threading.Thread(target = run1, args = ('b', ), daemon = True)
t3 = threading.Thread(target = run1, args = ('c', ), daemon = True)
t4 = threading.Thread(target = run_and_stop, args = ('d', ), daemon = True)
t1.start()
t2.start()
t3.start()
t4.start()

time.sleep(100)

Here the program should exit after 5s: the last thread reaches the interrupt_main() command, and since the other threads are daemon, they should all shut down then.

However it doesn't happen so. Can anyone explain me why and provide a solution for the program to exit then?

Answer 1

On Unix, time.sleep() uses select() . We could interrupt it by signaling the process, or explicitly the main thread, via kill() or pthread_kill() .

As for _thread.interrupt_main , from this discussion :

"Looking at the implementation, _thread.interrupt_main just calls PyErr_SetInterrupt. It doesn't appear to send a signal. I played with “strace” and couldn't see any evidence of a signal. I guess it just sets a flag that will be polled. To actually interrupt the “sleep” call, you might need to use “pthread_kill” or similar (at least on Unix)."

def run_and_stop(x):
    i = 0
    while True:
        time.sleep(1)
        print(x)
        i += 1
        if i == 5:
            os.kill(os.getpid(), signal.SIGINT)