p5pRT
commented
7 years ago From victor.burns@bankofamerica.com
This issue is believed to exist in all 5.10.1+ Perl's and every older Perl as well. I have verified the issue in every Perl I have at my disposal from 5.10.1 to 5.24.0
If the last reference to an object is in thread shared memory the objects DESTROY method won't be called or highly unlikely to be called. This is a *huge* problem for applications that are OO and designed using composition of other classes (HAS-A). The last\, and possibly only reference will be in Perl's thread shared memory. I think the real issue only resembles my description and therefore it is not perfect. I have however included a small script that when used and modified as the comments suggest the related behaviors may be observed. The actual issue is a bit more unpredictable.
## PERL BUG Example
use 5.010001; use strict; use warnings; use threads; use threads::shared;
our $VERSION = 0.1;
say 'Hello World!\, - Perl shared memory failure to call ->DESTROY detector.';
LEAKER: { ## Using the "shared" attribute can play a role in this ## Best guess it means all references are shared. my $aa :shared = bless &share({})\, 'Lazy::Crazy'; my $bb :shared = bless &share({})\, 'Lazy::Crazy'; my $cc :shared = &share( bless {}\, 'Lazy::Crazy' );
## Placing an object into another makes it a sure bet its ## ->DESTROY won't be called $aa->{ has_c } = $cc; $bb->{ has_a } = $aa;
## It's strange that the order of the following assignments ## will allow the last one touched to call its ->DESTROY $cc->{ label } = 'c'; $aa->{ label } = 'a'; $bb->{ label } = 'b';
## If I'm able to control the order these are unwrapped (destroyed) ## things start working as expected. ## How likely can I always get this right\, not at all! ## (uncomment and things work as expected) # $bb = undef; # $aa = undef; # $cc = undef; }
package Lazy::Crazy;
sub DESTROY { my $self = shift; printf "# %s '%s' is destroyed\n"\, ref $self\, $self->{ label }; return; }
## END
Migrated from rt.perl.org#130644 (status was 'rejected')
Searchable as RT130644$