How to execute code just before terminating the process in python?

Question

This question concerns multiprocessing in python. I want to execute some code when I terminate the process, to be more specific just before it will be terminated. I'm looking for a solution which works as atexit.register for the python program.

I have a method worker which looks:

def worker():
    while True:
        print('work')
        time.sleep(2)
    return

I run it by:

proc = multiprocessing.Process(target=worker, args=())
proc.start()

My goal is to execute some extra code just before terminating it, which I do by:

proc.terminate()

There is no way to do that since process.terminate() asks the operating system to kill with SIGTERM. So no finally handlers etc. will be executed. — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Mar 2, 2017 at 16:31
You can provide a SIGTERM signal handler. See signal.signal in docs.python.org/3.4/library/signal.html — Gil Hamilton
– Gil Hamilton, Commented Mar 2, 2017 at 16:35

leovp · Accepted Answer · 2017-03-02 16:37:37Z

4

Use signal handling and intercept SIGTERM:

import multiprocessing
import time
import sys
from signal import signal, SIGTERM

def before_exit(*args):
    print('Hello')
    sys.exit(0)  # don't forget to exit!


def worker():
    signal(SIGTERM, before_exit)
    time.sleep(10)

proc = multiprocessing.Process(target=worker, args=())
proc.start()
time.sleep(3)
proc.terminate()

Produces the desirable output just before subprocess termination.

answered Mar 2, 2017 at 16:37

leovp

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2 Comments

Spencer Sutton Over a year ago

Note that this will not work on Windows

djvg Over a year ago

related: stackoverflow.com/q/1216788

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