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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