NAME

Test::LeakTrace - Traces memory leaks

VERSION

This document describes Test::LeakTrace version 0.17.

SYNOPSIS

    use Test::LeakTrace;

    # simple report
    leaktrace{
        # ...
    };

    # verbose output
    leaktrace{
        # ...
    } -verbose;

    # with callback
    leaktrace{
        # ...
    } sub {
        my($ref, $file, $line) = @_;
        warn "leaked $ref from $file line\n";
    };

    my @refs = leaked_refs{
        # ...
    };
    my @info = leaked_info{
        # ...
    };

    my $count = leaked_count{
        # ...
    };

    # standard test interface
    use Test::LeakTrace;

    no_leaks_ok{
        # ...
    } 'no memory leaks';

    leaks_cmp_ok{
        # ...
    } '<', 10;

DESCRIPTION

"Test::LeakTrace" provides several functions that trace memory leaks. This module scans arenas, the memory allocation system, so it can detect any leaked SVs in given blocks.

Leaked SVs are SVs which are not released after the end of the scope they have been created. These SVs include global variables and internal caches. For example, if you call a method in a tracing block, perl might prepare a cache for the method. Thus, to trace true leaks, "no_leaks_ok()" and "leaks_cmp_ok()" executes a block more than once.

INTERFACE

Exported functions

"leaked_info { BLOCK }"

Executes BLOCK and returns a list of leaked SVs and places where the SVs come from, i.e. "[$ref, $file, $line]".

"leaked_refs { BLOCK }"

Executes BLOCK and returns a list of leaked SVs.

"leaked_count { BLOCK }"

Executes BLOCK and returns the number of leaked SVs.

"leaktrace { BLOCK } ?($mode | \&callback)"

Executes BLOCK and reports leaked SVs to *STDERR.

Defined $modes are:

-simple: Default. Reports the leaked SV identity (type and address), file name and line number.
-sv_dump: In addition to -simple, dumps the sv content using "sv_dump()", which also implements "Devel::Peek::Dump()".
-lines: In addition to -simple, prints suspicious source lines.
-verbose: Both -sv_dump and -lines.

"no_leaks_ok { BLOCK } ?$description"

Tests that BLOCK does not leaks SVs. This is a test function using "Test::Builder".

Note that BLOCK is called more than once. This is because BLOCK might prepare caches which are not memory leaks.

"leaks_cmp_ok { BLOCK } $cmp_op, $number, ?$description"

Tests that BLOCK leaks a specific number of SVs. This is a test function using "Test::Builder".

Note that BLOCK is called more than once. This is because BLOCK might prepare caches which are not memory leaks.

"count_sv()"

Counts all the SVs in the arena.

Script interface

Like "Devel::LeakTrace" "Test::LeakTrace::Script" is provided for whole scripts.

The arguments of "use Test::LeakTrace::Script" directive is the same as "leaktrace()".

    $ TEST_LEAKTRACE=-sv_dump perl -MTest::LeakTrace::Script script.pl
    $ perl -MTest::LeakTrace::Script=-verbose script.pl

    #!perl
    # ...

    use Test::LeakTrace::Script sub{
        my($ref, $file, $line) = @_;
        # ...
    };

    # ...

EXAMPLES

Testing modules

Here is a test script template that checks memory leaks.

    #!perl -w
    use strict;
    use constant HAS_LEAKTRACE => eval{ require Test::LeakTrace };
    use Test::More HAS_LEAKTRACE ? (tests => 1) : (skip_all => 'require Test::LeakTrace');
    use Test::LeakTrace;

    use Some::Module;

    leaks_cmp_ok{
        my $o = Some::Module->new();
        $o->something();
        $o->something_else();
    } '<', 1;

DEPENDENCIES

Perl 5.8.1 or later, and a C compiler.

CAVEATS

"Test::LeakTrace" does not work with "Devel::Cover" and modules which install their own "runops" routines, or the perl executor. So if the test functions of this module detect strange "runops" routines, they do nothing and report okay.

BUGS

No bugs have been reported.

Please report any bugs or feature requests to the author.

AUTHOR

Goro Fuji(gfx) <gfuji(at)cpan.org>.

LICENSE AND COPYRIGHT

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