I hope someone can shed some light on the following strange problem:

I'm using perl5.10 with mod_perl2 (ModPerl::Registry) / apache2, with a fairly big perl application consisting of quite a few own modules and a bunch of CPAN modules. Normally, when I do a die('whatever') in the code, or if there's a fatal error, this shows up in the error log like:

[Fri Jul 31 16:18:58 2009] [error] whatever at module.pm line 123

Lately I noticed that in certain cases, these errors disappear in some black hole. Don't know what happens with it and why. For example, this works fine:

#!/usr/bin/perl

use strict;
use Foo;

die('this will appear in the error log like expected');

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But the following will give nothing at all in the logs: 
#!/usr/bin/perl

use strict;
use Foo;

# here, something happens that messes up the die handler?
my $foo = Foo->new();

die('this will NOT appear in the error log at all');

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The following DOES give errors in the log:

#!/usr/bin/perl

use strict;
use Foo;

# here, something happens that messes up the die handler?
my $foo = Foo->new();
# but this apparently fixes it:
undef $foo;

die('this DOES appear in the error log');

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Unfortunately, the Foo module is company confidential so I cannot post the code of this module here. I checked the entire module, including all (direct and indirect) dependencies, but so far I haven't found anything suspicious. There's no weird perl magic going on, as far as I can tell. All scripts are CGI compatible so no specific mod_perl directives. There are a lot of modules "use"d however so it's like looking for a needle in the haystack..

This problem doesn't turn up on the command line. Nor does it when I use plain old CGI. Then everything works fine. So I figure it's got something to do with mod_perl.

I tried changing the die signal handler, I tried all of the following, but without the desired effect: (I also tried it without "local", no change)

local $SIG{__DIE__} = ''; # no effect
local $SIG{__DIE__} = 'DEFAULT'; # no effect

# this gives a warning in the error log, no error
local $SIG{__DIE__} = sub { warn @_ };

# this has no effect, nothing at all in the logs:
local $SIG{__DIE__} = sub { die @_ };

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For debugging purposes, redirecting the die to a warn is a viable workaround, but the application also contains a SOAP::Lite server, and in the server code, I use 

die SOAP::Fault->new(..);

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to throw Soap errors. The problem is that this doesn't work in cases described here; then, an empty Soap message is returned. That's a show stopper.

ATM, I don't know anymore where to look and what to look for, to solve this. Could anyone point me in a direction, or give me some suggestions I might try to solve this?

In reply to Disappearing fatal errors and die() with mod_perl2 by Farenji

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