Bug #28365 for Scalar-List-Utils: Segfault when a variable is destroyed after using weaken a large number of times (between 23K and 24K)

Wed Jul 18 10:51:05 2007 MIROD [...] cpan.org - Ticket created

Subject:

Segfault when a variable is destroyed after using weaken a large number of times (between 23K and 24K)

As per the descriptive title. I create a tree with a single root and thousands of children. The link from the root to the first child is strong, as is the link from each node to its next sibling. The link from each node to the root is weakened. The program crashes when the root goes out of scope. See the attached code which tries to find the esact number. Change the $NB_ELT_INIT and the $STEP values to find it. Note that the limit can vary (23790 and 23810 in my limited tests). I had the same problem with XML::Twig, which also builds a tree, at about the same number of nodes. Twig uses weaken several times for each node though, so that might be an element. Note that it is not the total number of weaken that counts, just the number in the block in which the variables are in scope. This behaviour happens in Scalar::Util 1.18 and 1.19 perl -v: This is perl, v5.8.8 built for i486-linux-gnu-thread-multi Note that I have had reports of bugs in XML::Twig that look suspiciously like they could come from this problem, on various machines (just today: Solaris in c.l.p.m, perl 5.8.5 and 5.8.8, and perl v5.8.7 built for i386-freebsd-64int by mail). I hope that helps __ mirod

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Wed Jul 18 20:09:37 2007 gbarr [...] pobox.com - Correspondence added

Subject:	Re: [rt.cpan.org #28365] Segfault when a variable is destroyed after using weaken a large number of times (between 23K and 24K)
Date:	Wed, 18 Jul 2007 19:09:07 -0500
To:	bug-Scalar-List-Utils [...] rt.cpan.org
From:	Graham Barr <gbarr [...] pobox.com>

On Jul 18, 2007, at 9:51 AM, via RT wrote: Show quoted text

> As per the descriptive title.

Scalar::Util::weaken is just giving access to a C function inside perl. If there is a bug with weak references then it should be reported using the perlbug script to report a core perl bug. Graham.

Wed Jul 18 20:09:41 2007 The RT System itself - Status changed from 'new' to 'open'

Wed Jul 18 21:41:30 2007 xmltwig [...] gmail.com - Correspondence added

Subject:	Re: [rt.cpan.org #28365] Segfault when a variable is destroyed after using weaken a large number of times (between 23K and 24K)
Date:	Thu, 19 Jul 2007 03:41:14 +0200
To:	bug-Scalar-List-Utils [...] rt.cpan.org
From:	"Michel Rodriguez" <xmltwig [...] gmail.com>

On 7/19/07, Graham Barr via RT <bug-Scalar-List-Utils@rt.cpan.org> wrote: Show quoted text

> > <URL: http://rt.cpan.org/Ticket/Display.html?id=28365 > > > On Jul 18, 2007, at 9:51 AM, via RT wrote:

> > As per the descriptive title.

> > Scalar::Util::weaken is just giving access to a C function inside > perl. If there is a bug with weak references then it should be > reported using the perlbug script to report a core perl bug.

Thanks Graham, I have just sent the bug report. -- mirod

Thu May 14 09:36:14 2009 GBARR [...] CPAN.ORG - Correspondence added

closing old ticket

Thu May 14 09:36:16 2009 GBARR [...] CPAN.ORG - Status changed from 'open' to 'resolved'