This probably has an easy answer, but why not have a single process
that monitors all children processes (instead of one per child).
Robert
On Nov 8, 2006, at 1:17 AM, William Stein wrote:
> Hi,
>
> I wrote an interesting little Python script, which I think will
> totally
> solve our "bad processes getting left around" problem. It's
> actually a
> very simple general purpose shell script, so I'm going to post it.
>
> The idea is that when SAGE spawns a process, it also spawns a monitor
> that watches to see if the parent sage process disappears -- if so, it
> kills the child process. It watches every five seconds.
>
> This monitor processes uses "0%" resources and 2MB memory on my
> laptop.
>
> This will be in SAGE-1.5.
>
> #!/usr/bin/env python
>
> # this goes in <SAGE_ROOT>/local/bin/sage-monitor
>
> import os, time, sys
>
> def check_usage():
> v = sys.argv
> if len(v) != 4:
> print "Usage: sage-monitor <master pid> <subprocess pid>
> <interval>"
> print "Runs the shell command checking every interval
> seconds"
> print "to see if there is a process with the given master
> pid."
> print "If not kill -9 the given subprocess pid and
> terminate."
> print "Also, if at any point the subprocess vanishes, then
> this"
> print "program exits."
> sys.exit(1)
>
> def process_is_running(pid):
> try:
> os.kill(pid,0)
> except OSError:
> # This means the process is not running
> return False
> return True
>
> def main():
> v = sys.argv
> pid = int(v[1])
> subprocess = int(v[2])
> interval = int(v[3])
>
> while True:
> if not process_is_running(subprocess):
> sys.exit(0)
> if not process_is_running(pid):
> # clean up house by killing subprocess
> try:
> os.killpg(subprocess, 9)
> except OSError, msg:
> pass
> try:
> os.kill(subprocess, 9)
> except OSError, msg:
> pass
> sys.exit(0)
> #end if
> time.sleep(interval)
>
> if __name__ == '__main__':
> check_usage()
> main()
>
> ------------------------------------------------------------
>
> # HG changeset patch
> # User William Stein <[EMAIL PROTECTED]>
> # Date 1162976220 28800
> # Node ID d49c043b5d80d25a524527dda1bf345b9b1dd97d
> # Parent 34bbca760915c3aa763f93cd8f22a1f6ae05d941
> Added starting a monitor shadow process to make sure any spawned
> processes
> are cleaned up properly on exit, even if the master SAGE process is
> kill
> -9'd. Cool!
>
> diff -r 34bbca760915 -r d49c043b5d80 sage/interfaces/expect.py
> --- a/sage/interfaces/expect.py Tue Nov 07 09:03:48 2006 -0800
> +++ b/sage/interfaces/expect.py Wed Nov 08 00:57:00 2006 -0800
> @@ -37,6 +37,9 @@ import sage.misc.sage_eval
> import sage.misc.sage_eval
>
> import quit
> +
> +import monitor
> +EXPECT_MONITOR_INTERVAL=5 # kill any slave processes at most 5
> seconds
> after parent dies.
>
> import sage.rings.coerce as coerce
> from sage.misc.misc import SAGE_ROOT, verbose, SAGE_TMP_INTERFACE
> @@ -230,12 +233,6 @@ class Expect(SageObject):
> os.makedirs(dir)
> os.chdir(dir)
>
> - # This _absolute call below programs around a bug in pexpect:
> - # make a directory X with a subdirectory "magma" and cd
> into X.
> Then:
> - #sage: import pexpect
> - #sage: m = pexpect.spawn('magma')
> - #sage: m.interact() # -- boom!
> -
> try:
> cmd = _absolute(self.__command)
> except RuntimeError:
> @@ -248,6 +245,7 @@ class Expect(SageObject):
>
> try:
> self._expect = pexpect.spawn(cmd,
> logfile=self.__logfile)
> + monitor.monitor(self._expect.pid,
> EXPECT_MONITOR_INTERVAL)
>
> except (pexpect.ExceptionPexpect, pexpect.EOF, IndexError):
> self._expect = None
> diff -r 34bbca760915 -r d49c043b5d80 sage/interfaces/monitor.py
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/sage/interfaces/monitor.py Wed Nov 08 00:57:00 2006 -0800
> @@ -0,0 +1,17 @@
> +#####################################################################
> ##########
> +# SAGE: System for Algebra and Geometry Experimentation
> +# Copyright (C) 2005, 2006 William Stein <[EMAIL PROTECTED]>
> +# Distributed under the terms of the GNU General Public License
> (GPL)
> +# The full text of the GPL is available at:
> +# http://www.gnu.org/licenses/
> +#####################################################################
> ##########
> +
> +
> +import os
> +
> +PID = os.getpid()
> +
> +def monitor(pid, interval):
> + cmd = 'sage-monitor %s %s %s &'%(PID, pid, interval)
> + os.system(cmd)
> +
>
> >
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