["python","multiprocessing","signals"]
Catch Ctrl+C / SIGINT and exit multiprocesses gracefully in python

How do I catch a Ctrl+C in multiprocess python program and exit all processes gracefully, I need the solution to work both on unix and windows. I've tried the following: import multiprocessing import time import signal import sys jobs = [] def worker(): signal.signal(signal.SIGINT, signal_handler) while(True): time.sleep(1.1234) print "Working..." def signal_handler(signal, frame): print 'You pressed Ctrl+C!' # for p in jobs: # p.terminate() sys.exit(0) if __name__ == "__main__": for i in range(50): p = multiprocessing.Process(target=worker) jobs.append(p) p.start() And it's kind of working, but I don't think it's the right solution.
The previously accepted solution has race conditions and it does not work with map and async functions. The correct way to handle Ctrl+C/SIGINT with multiprocessing.Pool is to: Make the process ignore SIGINT before a process Pool is created. This way created child processes inherit SIGINT handler. Restore the original SIGINT handler in the parent process after a Pool has been created. Use map_async and apply_async instead of blocking map and apply. Wait on the results with timeout because the default blocking waits to ignore all signals. This is Python bug https://bugs.python.org/issue8296. Putting it together: #!/bin/env python from __future__ import print_function import multiprocessing import os import signal import time def run_worker(delay): print("In a worker process", os.getpid()) time.sleep(delay) def main(): print("Initializng 2 workers") original_sigint_handler = signal.signal(signal.SIGINT, signal.SIG_IGN) pool = multiprocessing.Pool(2) signal.signal(signal.SIGINT, original_sigint_handler) try: print("Starting 2 jobs of 5 seconds each") res = pool.map_async(run_worker, [5, 5]) print("Waiting for results") res.get(60) # Without the timeout this blocking call ignores all signals. except KeyboardInterrupt: print("Caught KeyboardInterrupt, terminating workers") pool.terminate() else: print("Normal termination") pool.close() pool.join() if __name__ == "__main__": main() As @YakovShklarov noted, there is a window of time between ignoring the signal and unignoring it in the parent process, during which the signal can be lost. Using pthread_sigmask instead to temporarily block the delivery of the signal in the parent process would prevent the signal from being lost, however, it is not available in Python-2.