Re: [Boston.pm] perl 5.10 memory leak?

Yes!  That fixes it.  I'm not sure how 'local' makes a difference here, but it appears to work.

I figured out how to override the built-in version::boolean to fix it as well, but I like the "local" solution better.  Some of my testing shown here:

Failure exposing leak:
[mazu@cvm ~]$ perl -wE 'use Test::LeakTrace; use Data::Dumper;  $foo = version->new(v1.2.3); say @foo = ((Dumper leaked_refs { 1 if ($foo) }) || "clean")'
$VAR1 = \'0';
$VAR2 = \bless( {
                   'original' => '0',
                   'version' => [
                                  0
                                ]
                 }, 'version' );
$VAR3 = ${$VAR2}->{'version'};
$VAR4 = ${$VAR2};
$VAR5 = \${$VAR2}->{'version'}->[0];
$VAR6 = \${$VAR2}->{'original'};
$VAR7 = \${$VAR2}->{'version'};

Solution using "local":
[mazu@cvm ~]$ perl -wE 'use Test::LeakTrace; use Data::Dumper;  $foo = version->new(v1.2.3); say @foo = ((Dumper leaked_refs { local $foo; 1 if ($foo) }) || "clean")'
clean

Solution fixing version::boolean:
[mazu@cvm ~]$ perl -wE 'use Test::LeakTrace; use Data::Dumper; { no warnings "redefine"; *{"version::(bool"} = sub {  for my $v (@{$_[0]->{version}}) { return 1 if $v } return;  }} $foo = version->new(v1.2.3); say @foo = ((Dumper leaked_refs { 1 if ($foo) }) || "clean")'
clean

Also, I found another leak in comparing a version object to a non-version object ($^V eq $]) when playing around with Mike Small's suggestion.  Looks like this was also fixed at some point.

Duane

> On Dec 14, 2016, at 2:58 PM, Ben Tilly <[email protected]> wrote:
> 
> This is nasty.  Does the following fix work for you?
> 
> use IO::All;
> if ($^V lt v5.16.0) {
>   no warnings 'redefine';
>   my $orig_destroy = *IO::All::DESTROY{CODE};
>   *IO::All::DESTROY = sub {
>     my $self = shift;
>     local $^V;
>     $orig_destroy->($self, @_) if $orig_destroy;
>   };
> }
> 
> This temporarily replaces $^V with the empty string which does the right thing with the current version check.  Hopefully your Perl gets upgraded before IO::All has a new version check in DESTROY that this hack doesn't work.
> 
> On Wed, Dec 14, 2016 at 7:44 AM, Duane Bronson <[email protected] <mailto:[email protected]>> wrote:
> Ahh - the bug is in universal.c <https://perl5.git.perl.org/perl.git/blobdiff/202e6ee2081e3a898537656cda1148d9aded394d..bcb2959f0:/universal.c> in XS_version_boolean.  Can I override that in perl code?  Something like this?
> 
> sub version::boolean {
>   ...
> }
> 
> Thanks, Matthew!  I'd like to know how you found that.  Google didn't help me.
> Duane
> 
>> On Dec 14, 2016, at 12:58 AM, Matthew Horsfall (alh) <[email protected] <mailto:[email protected]>> wrote:
>> 
>> On Wed, Dec 14, 2016 at 12:55 AM, Matthew Horsfall (alh)
>> <[email protected] <mailto:[email protected]>> wrote:
>>> On Tue, Dec 13, 2016 at 6:41 PM, Ben Tilly <[email protected] <mailto:[email protected]>> wrote:
>>>> Is the leak in not calling untie, or in looking at $^V?
>>> 
>>> The leak is in looking at $^V. This was broken in 5.10.0 and fixed in 5.16.0.
>> 
>> In boolean context.
>> 
>>  my $x = $^V;  # fine
>>  my $x = !$^V; # bad
>>  if ($^V) { }       # bad
>> 
>> -- Matthew Horsfall (alh)
> 
> 
> 
> Duane Bronson
> [email protected] <mailto:[email protected]>
> http://www.nerdlogic.com/ <http://www.nerdlogic.com/>
> 5 Goden St.
> Belmont, MA 02478
> 617.515.2909
> 
> 
> 
> 
> 



Duane Bronson
[email protected] <mailto:[email protected]>
http://www.nerdlogic.com/ <http://www.nerdlogic.com/>
5 Goden St.
Belmont, MA 02478
617.515.2909