davem at iabyn
May 11, 2008, 1:02 PM
Post #2 of 8
(1466 views)
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On Thu, May 08, 2008 at 05:00:06PM -0400, Jerry D. Hedden wrote:
> While working on tests for some new threads::shared
> functionality, my test code started generating:
>
> Attempt to free unreferenced scalar: SV 0x15193f8, Perl
> interpreter: 0x14b2830 at ./leak.pl line 36.
> Attempt to free unreferenced scalar: SV 0x15193c8, Perl
> interpreter: 0x14b2830 at ./leak.pl line 36.
> Scalars leaked: 2
>
> The following (also attached) reproduces this in blead:
>
> #!/usr/bin/perl
> use strict;
> use warnings;
> use threads;
> use threads::shared;
>
> sub _bork {
> return $_[0];
> }
>
> sub bork
> {
> if (@_ != 1) {
> require Carp;
> Carp::croak('Needs one and only one arg');
> }
> return _bork(shift, {});
> }
>
> {
> my %hsh = ('foo' => 2);
> eval {
> bork(%hsh);
> };
> $@ = undef;
> }
>
> my $foo :shared;
> $foo = bork(\$foo);
>
> threads->create(sub {
> $foo = 1;
> })->join();
>
> I can remove 'use strict' and 'use warnings' and still
> reproduce the leak, but if I change anything else, the leak
> goes away.
>
> Can anyone else reproduce this? If so, can anyone identify
> what's leaking?
I can reproduce. It can be simplified to:
use threads;
use threads::shared;
sub bork {
if (@_) {
package DB;
() = caller(0);
}
return {};
}
{
my %hsh = ('foo' => 2);
eval {
bork(%hsh);
};
}
my $foo :shared;
bork();
threads->create(sub {
$foo;
})->join();
The two AV's that are being double-freed are the thread-cloned copies of
the pad and pad-name AVs of the cloned anon sub passed as an arg to
create().
I've run out of time to look at this any further for the moment.
--
"Procrastination grows to fill the available time"
-- Mitchell's corollary to Parkinson's Law
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leak.pl
