CatalystX::LeakChecker - Debug memory leaks in Catalyst applications

CatalystX-LeakChecker documentation Contained in the CatalystX-LeakChecker distribution.

Index

Code Index:

NAME

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CatalystX::LeakChecker - Debug memory leaks in Catalyst applications

VERSION

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version 0.06

SYNOPSIS

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    package MyApp;
    use namespace::autoclean;

    extends 'Catalyst';
    with 'CatalystX::LeakChecker';

    __PACKAGE__->setup;

DESCRIPTION

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It's easy to create memory leaks in Catalyst applications and often they're hard to find. This module tries to help you finding them by automatically checking for common causes of leaks.

This module is intended for debugging only. I suggest to not enable it in a production environment.

METHODS

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found_leaks(@leaks)

If any leaks were found, this method is called at the end of each request. A list of leaks is passed to it. It logs a debug message like this:

    [debug] Circular reference detected:
    +------------------------------------------------------+-----------------+
    | $ctx->{stash}->{ctx}                                                   |
    '------------------------------------------------------+-----------------'

It's also able to find leaks in code references. A debug message for that might look like this:

    [debug] Circular reference detected:
    +------------------------------------------------------+-----------------+
    | $a = $ctx->{stash}->{leak_closure};                                    |
    | code reference $a deparses to: sub {                                   |
    |     package TestApp::Controller::Affe;                                 |
    |     use warnings;                                                      |
    |     use strict 'refs';                                                 |
    |     $ctx->response->body('from leaky closure');                        |
    | };                                                                     |
    | ${ $ctx }                                                              |
    '------------------------------------------------------+-----------------'

Override this method if you want leaks to be reported differently.

AUTHORS

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Florian Ragwitz <rafl@debian.org> Tomas Doran <bobtfish@bobtfish.net>

COPYRIGHT AND LICENSE

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This software is copyright (c) 2010 by Florian Ragwitz.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

CatalystX-LeakChecker documentation Contained in the CatalystX-LeakChecker distribution. 
package CatalystX::LeakChecker;
our $VERSION = '0.06';
# ABSTRACT: Debug memory leaks in Catalyst applications

use Moose::Role;
use B::Deparse;
use Text::SimpleTable;
use Scalar::Util 'weaken';
use Devel::Cycle 'find_cycle';

sub deparse {
    my ($code) = @_;
    return q{sub } . B::Deparse->new->coderef2text($code) . q{;};
}

sub format_table {
    my @leaks = @_;
    my $t = Text::SimpleTable->new([52, 'Code'], [ 15, 'Variable' ]);
    $t->row(@$_) for map { [deparse($_->{code}), $_->{var}] } @leaks;
    return $t->draw;
}

sub format_leak {
    my ($leak, $sym) = @_;
    my @lines;
    my $ret = '$ctx';
    for my $element (@{ $leak }) {
        my ($type, $index, $ref, $val, $weak) = @{ $element };
        die $type if $weak;
        if ($type eq 'HASH') {
            $ret .= qq(->{$index}) if $type eq 'HASH';
        }
        elsif ($type eq 'ARRAY') {
            $ret .= qq(->[$index]) if $type eq 'ARRAY';
        }
        elsif ($type eq 'SCALAR') {
            $ret = qq(\${ ${ret} });
        }
        elsif ($type eq 'CODE') {
            push @lines, qq(\$${$sym} = ${ret};);
            push @lines, qq{code reference \$${$sym} deparses to: } . deparse($ref);
            $ret = qq($index);
            ${ $sym }++;
        }
    }
    return join qq{\n} => @lines, $ret;
}

use namespace::clean -except => 'meta';


sub found_leaks {
    my ($ctx, @leaks) = @_;
    my $t = Text::SimpleTable->new(70);

    my $sym = 'a';
    for my $leak (@leaks) {
        $t->row(format_leak($leak, \$sym), '');
    }

    my $msg = "Circular reference detected:\n" . $t->draw;
    $ctx->log->debug($msg) if $ctx->debug;
}

after finalize => sub {
    my ($ctx) = @_;
    my @leaks;

    my $weak_ctx = $ctx;
    weaken $weak_ctx;

    find_cycle($ctx, sub {
        my ($path) = @_;
        push @leaks, $path
            if $path->[0]->[2] == $weak_ctx;
    });
    return unless @leaks;

    $ctx->found_leaks(@leaks);
};

1;

__END__