[Lxr-dev] $SIG{__DIE__} considered harmful in a mod-perl environment?

[Jens-Uwe M. <ju...@he...>]

I have been chasing a strange error in my installation for a while that
I finally nailed down today. Occasionally users did mention to me that they
see strange error messages in their HTML pages that do mention they are
generated by LXR even though they are not on any page that is generated
by LXR. I do use also HTML::Embperl and other perl modules so most of
the pages do use some perl in any case, and I found that some pages use
eval statements to check for availability of modules.

If LXR happened to run once in that particular httpd then the problem
occurs that LXR happens to issue error messages for failing eval
statements even though it is not really associated to these. This
happens as mod-perl does implement a shared interpreter for all the
scripts, and some of the interpreter resources are shared across all
scripts loaded into mod-perl. In particular here the problem is httpinit
in LXR::Common.pm, which does modify (pseudo) signal handlers:

sub httpinit {
        $SIG{__WARN__} = \&warning;
	$SIG{__DIE__}  = \&fatal;

These are shared across all scripts and thus fatal or warning gets
called even though LXR is not processing a request currently. Would it
be possible to get around without setting these signal handlers? Looking
into the mod-perl mailing list archive it looks like this usage is
considered harmful in the mod-perl environment.

-- 
Jens-Uwe Mager

HELIOS Software GmbH
Steinriede 3
30827 Garbsen
Germany

Phone:		+49 5131 709320
FAX:		+49 5131 709325
Internet:	ju...@he...