Test::LeakTrace(3) User Contributed Perl Documentation Test::LeakTrace(3)

Test::LeakTrace - Traces memory leaks

This document describes Test::LeakTrace version 0.17.

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;

"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.

"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.

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) = @_;
    # ...
};

# ...

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;

Perl 5.8.1 or later, and a C compiler.

"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.

No bugs have been reported.

Please report any bugs or feature requests to the author.

Devel::LeakTrace.

Devel::LeakTrace::Fast.

Test::TraceObject.

Test::Weak.

For guts:

perlguts.

perlhack.

sv.c.

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

Copyright (c) 2009-2010, Goro Fuji(gfx). All rights reserved.

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

2021-05-24 perl v5.34.0