using SIGKILL is not a good way to end processes and zombies are evil not only in "Night of the Living Dead"<https://en.wikipedia.org/wiki/Night_of_the_Living_Dead> ;-) they consume resources.
mic 2012/11/8 Richard Baron Penman <richar...@gmail.com> > thanks for advice, but already have a working solution. > > > It's still not clear why the scheduler does not fit your needs. > I do not need to schedule tasks. I just need to react to form submissions > so having the scheduler middleman is not necessary in this case. > > > > On Fri, Nov 9, 2012 at 12:59 AM, Michele Comitini < > michele.comit...@gmail.com> wrote: > >> It's still not clear why the scheduler does not fit your needs. Anyway >> what you want seems to need should be a *deamon*. >> You can launch it in the middle of the request/response cycle or from the >> scheduler it will detach from the parent (the launching) process and work >> in the background. >> >> pip install python-daemon >> >> http://pypi.python.org/pypi/python-daemon/ >> >> >> mic >> >> >> 2012/11/7 Richard Baron Penman <richar...@gmail.com> >> >>> OK, got a solution that has been working well for last few days now. >>> >>> I made 2 mistakes previously that caused me trouble: >>> >>> 1) The child processes are independent. I had used ctrl+c to kill >>> web2py, which was passed on to the child processes. >>> When kill -9 [web2py PID] was used the child processes continued fine. >>> >>> 2) The parent process can kill child processes but they became zombie >>> processes until the parent process dies. >>> Originally I was checking /proc/PID for process existence so seemed to >>> always exist. Now using the psutil package, which has some useful >>> cross platform features. Much better than parsing output of ps! >>> >>> >>> The scheduler was not helpful for this use case. >>> >>> Here are some functions I used in case they help others: >>> >>> >>> def exists(pid): >>> """Return whether the process exists""" >>> try: >>> p = psutil.Process(pid) >>> if p.status == psutil.STATUS_ZOMBIE: >>> return False # ignore zombie processes >>> else: >>> return True >>> except psutil.NoSuchProcess: >>> return False >>> >>> >>> def stop(pid): >>> """Try to kill this process, first with interrupt and then kill >>> signal >>> """ >>> success = True >>> try: >>> p = psutil.Process(pid) >>> p.terminate() >>> time.sleep(1) # if don't delay here a bit then exists() call >>> will usually fail - better way? >>> if exists(pid): >>> # was not able to terminate process so try kill >>> p.kill() >>> time.sleep(1) >>> if exists(pid): >>> success = False >>> except psutil.NoSuchProcess: >>> pass >>> return success >>> >>> -- >>> >>> >>> >>> >> -- >> >> >> >> > > -- > > > > --
