[EMAIL PROTECTED] wrote: > On Feb 8, 7:04 am, Larry Bates <[EMAIL PROTECTED]> wrote: >> [EMAIL PROTECTED] wrote: >>> I'm developing a program that runs using an asyncore loop. Right now >>> I can adequately terminate it using Control-C, but as things get >>> refined I need a better way to stop it. I've developed another >>> program that executes it as a child process using popen2.Popen4(). I >>> was attempting to use signals to stop it (using os.kill()) but I keep >>> running into a problem where sending the signal causes an infinite >>> loop of printing the message "warning: unhandled exception". This >>> message appears to be coming from asyncore.py. >>> Searching online I've found this old post that describes setting up a >>> signal handler using signal.signal(): >>> http://mail.python.org/pipermail/medusa-dev/2000/000571.html >>> I've tried it but I don't see any indication that my handler method is >>> being called. My best guess is that something somewhere else is >>> overriding my signal handling callbacks and sending the signals >>> elsewhere until they make their way into asyncore where they cause the >>> error message. >>> Any other ideas on how to get this to work? If there's a different >>> signal I can use that other code won't override, that's fine (I don't >>> care what the signal is, as long as I can catch it). Or perhaps there >>> is something different I can do? The program, at present, doesn't >>> have much in the way of an internal shutdown mechanism. >>> I'm using Python 2.5.1 on Fedora 8; the program does not need to be >>> portable to Windows. >>> - David >>> (p.s. please post replies on the list; this email address doesn't work >>> so I won't see any replies sent directly to me) >> Please share a little of the code you used to "catch" the signal. What >> signal(s) are you catching? What kill level are you sending (these have to >> match up). I've used this quite successfully in some of my programs. >> >> -Larry > > Sure. First, here is the signal I'm sending, from the parent process: > > os.kill(self.child.pid, signal.SIGTERM) > > self.child is the popen2.Popen4 object returned from creating the > child process. > > In the child process, one of the first things in the "main" section > (if __name__ == '__main__':) is to set up the signal handler: > > signal.signal(signal.SIGTERM, handle_shutdown_signal) > > handle_shutdown_signal looks a lot like Sam Rushing's example code > from his 2000 post, though I didn't see much of a reason to have the > callback function turn around and call another function, so I combined > them: > > SHUTDOWN_PERFORMED = False > > def handle_shutdown_signal(signum, frame): > global SHUTDOWN_PERFORMED > print 'in shutdown handler, caught signal', signum #diagnostic msg > if not SHUTDOWN_PERFORMED: > #do some stuff > asyncore.socket_map.clear() > SHUTDOWN_PERFORMED = True > raise asyncore.ExitNow > > I also tried replacing the raise asyncore.ExitNow command with a > simple exit() call but that didn't help. > > I've also tried using SIGHUP and SIGKILL and they didn't seem to make > a difference. > > - David
When signal is caught handle_shutdown_signal is called. At that point SHUTDOWN_PERFORMED will ALWAYS be False. Normally all you do in this function is to set SHUTDOWN_PERFORMED to True and have a test somewhere in your main program loop that tests if SHUTDOWN_PERFORMED:... I know that when you reach if not SHUTDOWN_PERFORMED: SHUTDOWN_PERFORMED will always be False so #do some stuff will get executed. Setting SHUTDOWN_PERFORMED = True doesn't do any good unless you catch this back in the main program. If I were you I would try to issue kill from console first to see if it works. Then try os.kill(). Hope this helps some. -Larry -- http://mail.python.org/mailman/listinfo/python-list
