在多处理中清理子进程

Question

Consider simple setup of a child process. Basically, it is a producer(parent)-consumer(child) scenario.

class Job:
    def start_process(self):
        self.queue = multiprocessing.Queue(3)
        self.process = multiprocessing.Process(target=run,
                                               args=(self.queue))

def run(queue):
    while True:
        item = queue.get()
        ....

If I do kill -9 on the parent process the child will hang forever. I was sure that it will receive SIGHUP like with subprocess.Popen - when the python process quits the popen ed will quit as well. Any idea how to fix child cleanup?

Answer 1

If the daemon param doesn't work for you, you can catch a SIGINT signal and have it set a boolean value to exit the while loop in your children. ie..

import signal

g_run_loops = True
def signal_handler(signum, frame):
   global g_run_loops
   g_run_loops = False

signal.signal(signal.SIGINT, signal_handler)

def run(queue):
    global g_run_loops
    while g_run_loops:
        item = queue.get()
        ....

Note that this won't work for SIGKILL (kill -9) but should work for SIGINT (kill -2).