python Popen: How do I stop(kill) the subprocess that created using Popen?

Question

I need to stop the service(runs at the background in another thread) that I issued through Popen in python after I got the result, but the following approach failed(just use ping for the sake of explanation):

class sample(threading.Thread): def __init__(self, command, queue): threading.Thread.__init__(self) self.command = command; self.queue = queue def run(self): result = Popen(self.command, shell=True, stdout=PIPE, stderr=STDOUT) while True: output = result.stdout.readline() if not self.queue.empty(): result.kill() break if output != "": print output else: break def main(): q = Queue() command = sample("ping 127.0.0.1", q) command.start() time.sleep(10) q.put("stop!") command.join() if __name__ == "__main__": main()

After running above program, when I pgrep for ping, it's still there. How can I kill the subprocess opened by Popen? Thanks.

PS: I also tried result.terminate(), but doesn't really solve the problem either.

@Keith: When I do ps aux | grep ping, it gives out the ping process running, if I don't use "kill", they are always there. — Shang Wang
– Shang Wang, Commented Apr 9, 2012 at 20:43
It may be there, but what's it's status? I'm wondering if you just don't have to wait() on the subprocess (it's a zombie process). — Keith
– Keith, Commented Apr 9, 2012 at 20:47
@Keith: The status for the remaining thread is "S+", and it is created with another process when the command is issued. Do you think that it's the zombie process? How does that affect my process? — Shang Wang
– Shang Wang, Commented Apr 9, 2012 at 20:55

Keith · Accepted Answer · 2012-04-09 21:06:06Z

You don't really need to run a subprocess from a thread. Try running the subprocess without a thread. Also, you specified shell=True, so it's running the command in a shell. So there are two new processes, the shell and the command. You can also remove the shell by making shell=False.

Great job my friend, simply change the shell=False, and the result.terminate() will terminate the process. Thanks.

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