I'm trying to use atexit
in a Process
, but unfortunately it doesn't seem to work. Here's some example code:
import time
import atexit
import logging
import multiprocessing
logging.basicConfig(level=logging.DEBUG)
class W(multiprocessing.Process):
def run(self):
logging.debug("%s Started" % self.name)
@atexit.register
def log_terminate():
# ever called?
logging.debug("%s Terminated!" % self.name)
while True:
time.sleep(10)
@atexit.register
def log_exit():
logging.debug("Main process terminated")
logging.debug("Main process started")
a = W()
b = W()
a.start()
b.start()
time.sleep(1)
a.terminate()
b.terminate()
The output of this code is:
DEBUG:root:Main process started DEBUG:root:W-1 Started DEBUG:root:W-2 Started DEBUG:root:Main process terminated
I would expect that the W.run.log_terminate()
would be called when a.terminate()
and b.terminate()
are called, and the output to be something likeso (emphasis added)!:
DEBUG:root:Main process started DEBUG:root:W-1 Started DEBUG:root:W-2 Started DEBUG:root:W-1 Terminated! DEBUG:root:W-2 Terminated! DEBUG:root:Main process terminated
Why isn't this working, and is there a better way to log a message (from the Process
context) when a Process
is terminated?
Thank you for your input - it's much appreciated.
Solution
EDIT: Based on solution suggested by Alex Martelli, the following works as expected:
import sys
import time
import atexit
import signal
import logging
import multiprocessing
logging.basicConfig(level=logging.DEBUG)
class W(multiprocessing.Process):
def run(self):
logging.debug("%s Started" % self.name)
def log_terminate(num, frame):
logging.debug("%s Terminated" % self.name)
sys.exit()
signal.signal(signal.SIGTERM, log_terminate)
while True:
time.sleep(10)
@atexit.register
def log_exit():
logging.debug("Main process terminated")
logging.debug("Main process started")
a = W()
b = W()
a.start()
b.start()
time.sleep(1)
a.terminate()
b.terminate()
It's worthwhile to note the following comment in the atexit
documentation:
Note: the functions registered via this module are not called when the program is killed by a signal, when a Python fatal internal error is detected, or when os._exit() is called.