[Zope] System performance threads/proccesses & random crashes (SIGPIPE)

[Chris McDonough]

You know, something comes to mind.  When a UNIX process forks, it copies its
signal handler state to the child's process space.  I dont know exactly how
the FastCGI stuff invokes Zope, but it may be that Python only installs a
SIGPIPE SIG_IGN handler if one isn't inherited from a parent process.
Setting it explicitly in z2.py ala the below message might cause your
problem to be solved if so.

----- Original Message -----
From: "Chris McDonough" <chrism@zope.com>
To: "Doyon, Jean-Francois" <Jean-Francois.Doyon@CCRS.NRCan.gc.ca>;
<zope@zope.org>; <matt@zope.com>
Sent: Friday, March 22, 2002 4:41 PM
Subject: Re: [Zope] System performance threads/proccesses & random crashes
(SIGPIPE)


> > A couple of more things:
> >
> > This, so far as I can tell is a bug in the FastCGI implementation (Not
> > handling SIGPIPE as suggested).  Should I report it somewhere?
>
> The bit you passed along from the FastCGI website seems to intimate that
the
> behavior is expected... I'm not sure where you would report it. ;-)
>
> > Python installs a small number of signal handlers by default: SIGPIPE is
> > ignored (so write errors on pipes and sockets can be reported as
ordinary
> > Python exceptions)
>
> I didn't know this.  It appears Python already installs SIG_IGN as the
> signal handler for a SIGPIPE signal... mm.  I'm not sure how your
> configuration manages to get around this. I'd have to guess that some
> product is resetting the signal handler.
>
> > And finally, how do I "ignore" a signal ? I guess just writing a "pass"
> > will work ? I'll try it out, I guess on reception of a signal, only one
> > handler is a called once?
>
> import signal
> signal.signal(signal.SIGPIPE, signal.SIG_IGN)
>
> This installs a null signal handler for the SIGPIPE signal.
>
> I wonder if you could find the place in the code where the exception
occurs
> when you click a lot and place a "print signal.getsignal(signal.SIGPIPE)"
> right before the place that the error happens.  See if it's 1.  If it's
1...
> well, I'm not sure.  I dont know how the process could be killed by a
SIGPIE
> then.
>
> If it's 0, that means that something has installed a signal handler on top
> of Python's default "ignore SIGPIPE" signal handler, and you might be able
> to find it by grepping for "SIGPIPE" or "13" in your code.
>
> - C
>
>
>
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