[Buildbot-devel] Zombie process warning

[Christian Lins]

Hi!

Brian Warner schrieb:
> Weird, I haven't seen that problem before. What platform is this on? And what
> reactor is it using? (grep for "reactor class" in twistd.log).
> 

I am using Buildbot/0.7.9 on Ubuntu/8.04 (x86).

cat twistd.log | grep reactor
2008-09-17 11:40:32+0200 [-] reactor class: <class
'twisted.internet.selectreactor.SelectReactor'>
2008-09-22 10:18:30+0200 [-] reactor class: <class
'twisted.internet.selectreactor.SelectReactor'>

> When the process starts, a reactor is installed (something like
> selectreactor, pollreactor, glibreactor, etc). When the reactor starts up,
> it's supposed to register a signal handler for the SIGCHLD signal: this is
> used to catch the SIGCHLD that occurs when a child process finishes.
> 
> The 'buildbot restart' command spawns a child process to watch the buildbot's
> twistd.log: it looks for errors and warnings, and waits until it sees the
> line that indicates the buildmaster/buildslave has started properly, then it
> exits.

In fact the message appears on "buildbot start" as well.

../bin/buildbot start .
Following twistd.log until startup finished..
/home/sun/eclipse/bbtermite/buildbot/scripts/logwatcher.py:48:
PotentialZombieWarning: spawnProcess called, but the SIGCHLD handler is
not installed. This probably means you have not yet called reactor.run,
or called reactor.run(installSignalHandler=0). You will probably never
see this process finish, and it may become a zombie process.
  env=os.environ,
2008-09-22 10:18:30+0200 [-] Log opened.
2008-09-22 10:18:30+0200 [-] twistd 8.1.0 (/usr/bin/python 2.5.2)
starting up

Perhaps this was all my fault as I noticed here that I had the twistd
8.1 installed which is from Ubuntu/8.10 not 8.04, sorry for that ;)

A reinstalled twistd 2.5 and the message disappeared...

> hope that helps,

Yes, very interesting explanation. Thank you :)

Regards,
Christian