[rt-devel] debug info on memory leaks under mod_perl.

[Jesse Vincent]

On Mon, Oct 20, 2003 at 07:41:51PM +0400, Ruslan U. Zakirov wrote:
> 		Hello, RT hackers :)
> 	I want to remember to you that RT leaks.
> 
> 	While my last hacking on RT I've understood that Perl and CPAN 
> 	modules could be buggy too and at first time complain on them. But after 13 
> hours of fighting with Apache::Leak, B::LexInfo, die 'Test', 
> Data::Dumper and other similar shit I figured out that it's almost only 
> RT problem.
> 
> 	The problem is circular references.
> Good article about it here:
> http://www.perl.com/pub/a/2002/08/07/proxyobject.html
> 
> We leak at least one CurrentUser object + all object on which it has 
> pointer(PrincipalObj, UserObj...) Why? Because of 'user' references on 
> CurrentUser which have each object inherited from RT::Handle and 
> RT::Record. And also CurrentObject itself have such pointer. So after 
> untie of %session perl never call DESTROY on this objects.
> 
> 1) weaken solution is good, but have issues
> 	a) perl should be >5.6.0, but it's not a problem for RT. RT have 
> 	same requirments.

The following change has been made to RT::Base:

    sub CurrentUser {
        my $self = shift;
    
        if (@_) {
            $self->{'user'} = shift;
|+          Scalar::Util::weaken($self->{'user'}) if (ref($self->{'user'}) &&
|+                                                      $self->{'user'} == $self );
        }


With this in place, RT passes all tests and the following test script
shows that object destruction is taking place immediately:

sh-2.05a# more memtest
#!/usr/bin/perl

use lib qw(/opt/rt3/lib);
use RT;
RT::LoadConfig();
RT::Init();

use RT::CurrentUser;
sub RT::CurrentUser::DESTROY {
    print "HULK SMASH!\n";
}
for (my $i = 1; $i <= 500; $i++) {
    print "Loading user $user...";
    my $user = RT::CurrentUser->new('root');

}

print "Done";





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