NAME

Debugging mod_perl Perl Internals

Description

This document explains how to debug Perl code under mod_perl.

Most of the mod_perl 1.0 debug documentation applies to mod_perl 2.0:

Detecting Hanging Processes

See Hanging Processes: Detection and Diagnostics for the explanation, but under mp2 to use signals to detect where the process is spinning, you can't use $SIG{USR2}, you have to use POSIX signals. i.e. the code becomes:

use Carp ();
use POSIX qw(SIGUSR2);
my $mask      = POSIX::SigSet->new( SIGUSR2 );
my $action    = POSIX::SigAction->new(\&tell_where_spinning, $mask);
my $oldaction = POSIX::SigAction->new();
POSIX::sigaction(SIGUSR2, $action, $oldaction );

sub tell_where_spinning {
    Carp::confess("caught SIGUSR2!");
};

and then:

% kill USR2 <pid_of_the_spinning_process>

and watch for the trace in error_log.

Maintainers

Maintainer is the person(s) you should contact with updates, corrections and patches.

• Stas Bekman <stas (at) stason.org>

Authors

• Stas Bekman <stas (at) stason.org>

Only the major authors are listed above. For contributors see the Changes file.