in reply to Re^2: Segmentation fault from XML::Twig::Elt
in thread Segmentation fault from XML::Twig::Elt

I can reproduce the problem in win32 (perl 5.12.3), but not on linux (perl5.12.3, 5.12.4 or 5.14.2). So since it's the same code on all 3 versions, I would think it's a bug somewhere in Scalar::Util::weaken or in the core, but only on windows. Which is a bit annoying since I don't develop on windows, I only use it to test modules before a release.

I am not sure where to go from there honestly. Any idea?

  • Comment on Re^3: Segmentation fault from XML::Twig::Elt

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Re^4: Segmentation fault from XML::Twig::Elt
by isync (Hermit) on Nov 07, 2011 at 14:07 UTC
    Most in this thread already is beyond my knowledge of the internal workings,
    but I can contribute that I got this error on a:
    Debian 4.0 box with Perl v5.10.0 built for i486-linux-gnu-thread-multi with these module versions:
    Read more... (917 Bytes)
    and on
    Ubuntu 11.04 with Perl v5.10.1 (*) built for i686-linux-gnu-thread-multi.
[reply]
Re^4: Segmentation fault from XML::Twig::Elt
by Anonymous Monk on Nov 08, 2011 at 04:46 UTC
[reply]

      The bug is in Perl itself, and seems to be fixed in 5.15.5.

      The following code, which is the simplest I have found to trigger the problem, causes a segmentation fault for versions up to 5.14.2, but not in 5.15.5 or bleadperl:

      
#!/usr/bin/perl

use strict;
use warnings;

use Scalar::Util 'weaken';

# the number of iteration that causes a segmentation fault varies
# on my machine, 5.14.2 18700, 5.12.4 20147, blead 
# at these values, the bug shows up most of the time but not always

my $ITER= $ARGV[0] || 18700;

my $head= {};
my $tail= $head;

foreach (1..$ITER)
  { my $new_tail= { p => $tail };
    weaken( $new_tail->{p});
    $tail->{n}=  $new_tail;
    $tail= $new_tail;
  }

print "done\n";

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