Devel::Leak and leaking code

Sisyphus Wed, 08 Dec 2004 18:07:24 -0800

Hi,

This is really a usage question - of how to use Devel::Leak to demonstrate memory leaks - instigated by a post by Tels on the same topic last week (blame him :-)

------------------------------------
use warnings;
use strict;
use Devel::Leak;

use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C => <<'EOC';

char * leaker1(int s) {
       char * r;
       int i;

       Newz(1, r, sizeof(char) * s, char);
       if(r == NULL) croak("Failed to allocate memory in leaker1()");

       for(i = 0; i < s-1; ++i) r[i] = 50;

       return r;
}

SV * leaker2(int s) {
       char * r;
       int i;

       Newz(1, r, sizeof(char) * s, char);
       if(r == NULL) croak("Failed to allocate memory in leaker1()");

       for(i = 0; i < s-1; ++i) r[i] = 50;

       return newSVpv(r, 0);
}

EOC

my $leakhandle;
my $leakcount = Devel::Leak::NoteSV($leakhandle);

leaktest1(); print "Leaked ", Devel::Leak::CheckSV($leakhandle) - $leakcount, " things\n";

# $leakcount = Devel::Leak::NoteSV($leakhandle);

#leaktest2(); #print "Leaked ", Devel::Leak::CheckSV($leakhandle) - $leakcount, " things\n";

sub leaktest1{
    for(2..5000) {
       my $str = leaker1($_);
       }
    print "Leaving leaktest1()\n";
}

sub leaktest2{
    for(2..5000) {
       my $str = leaker2($_);
       }
    print "Leaving leaktest2()\n";
}

__END__

As I understand it, both the leaker1() and leaker2() functions will leak memory, but I'm unable to get Devel::Leak to report it using the above script.

If I run either the leaktest1() or the leaktest2() subroutine then I get a report of 0 leakages. Things can get a little crazy if I run both subroutines in the one execution of the script. If I don't reset $leakcount between the running of leaktest1() and leaktest2(), then leaktest1() still reports 0 leakages, but leaktest2() dumps out the addresses of a number of leaked items - and then the script segfaults. If I *do* reset $leakcount between the running of the 2 subs, then both leaktest1() and leaktest2() again report a leakage 0 items.

Well .... I don't really need an explanation of *all* of that .... if someone can just show me the correct way to demonstrate the memory leaking capability of the code using Devel::Leak, that would be great .... that is, if it *can* be done.

Cheers,
Rob

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Devel::Leak and leaking code

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