Random corrupted double-linked list

ghenry has asked for the wisdom of the Perl Monks concerning the following question:

Hi all,

Where do I start with debugging something like this? Do I re-compile with debugging symbols and see what's in the backtrace?

*** glibc detected *** t/03create_customer.t: corrupted double-linked 
+list: 0x0db445f8 ***
======= Backtrace: =========
/lib/i686/nosegneg/libc.so.6[0xa617f6]
/lib/i686/nosegneg/libc.so.6[0xa63a67]
/lib/i686/nosegneg/libc.so.6[0xa6549e]
/lib/i686/nosegneg/libc.so.6(realloc+0xed)[0xa6614d]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_safesysrealloc+0x47)[0xbe32c7]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_grow+0x74)[0xc10744]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_catpvn_flags+0x11a)[0xc1150a]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_catsv_flags+0xf8)[0xc167b8]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_pp_require+0x14ce)[0xc30a3e]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_runops_standard+0x1f)[0xbf8f5f]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_call_sv+0x46d)[0xb9867d]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_clear+0xb7)[0xc0cca7]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_free2+0x58)[0xc0d4e8]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_free+0xd6)[0xc0d606]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so[0xc0ddc0]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so[0xc028e0]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(Perl_sv_clean_objs+0x3a)[0xc0294a]
/home/ghenry/perl5/perlbrew/perls/perl-5.10.1/lib/5.10.1/i686-linux-th
+read-multi/CORE/libperl.so(perl_destruct+0x11c8)[0xb9d2a8]
t/03create_customer.t(main+0xd7)[0x80489d7]
/lib/i686/nosegneg/libc.so.6(__libc_start_main+0xdc)[0xa0ee9c]
t/03create_customer.t[0x8048841]
[download]

Thanks.

Walking the road to enlightenment... I found a penguin and a camel on the way.....
Fancy a yourname@perl.me.uk? Just ask!!!

Comment on Random corrupted double-linked list Download Code

Replies are listed 'Best First'.
Re: Random corrupted double-linked list by dave_the_m (Monsignor) on Feb 13, 2012 at 18:44 UTC
Well, here are some random observations. The backtrace in question shows that a destructor is being called during global destruction; that destructor is calling require - not illegal, but unusal; require is creating a string of some sort, and while trying to grow it, the system malloc detects some internal corruption. This usually means that something corrupted it earlier; either due to a bug in perl, or a bug in an XS module that was earlier loaded. Building with debugging symbols will get you line numbers and function arguments, while building with Configure -DDEBUGGING may trigger an earlier assertion. But if you're on a system that supports it, you'll be best off using valgrind to see what's happening. Finally, 5.10.1 is quite old; it may be that a bug is already fixed in 5.12.4 or 5.14.2. Dave	[reply]
Re^2: Random corrupted double-linked list by ghenry (Vicar) on Feb 13, 2012 at 19:33 UTC
OK, great. I only chose 5.10.1 as that is what comes with Debian Squeeze and installed 5.10.1 on CentOS which is the Devel VM. I control all ENVs so there's no reason I can't go to 5.14.2 I'll do that in case something else comes along, then use valgrind. Both prod, test and dev will then get the same everything. Thanks. Walking the road to enlightenment... I found a penguin and a camel on the way..... Fancy a yourname@perl.me.uk? Just ask!!!	[reply]
Re^2: Random corrupted double-linked list by ghenry (Vicar) on Feb 13, 2012 at 23:23 UTC
That's 5.14.2 in and all my Catalyst app requirements installed. Just running `script/surevoip_api_server.pl` produces a Segmentation fault.... Walking the road to enlightenment... I found a penguin and a camel on the way..... Fancy a yourname@perl.me.uk? Just ask!!!	[reply] [d/l]
Re^3: Random corrupted double-linked list by chrestomanci (Priest) on Feb 14, 2012 at 15:41 UTC
It sounds like you have found a bug in perl. Kudos to you, especially if no one else has found and reported it before you. Two things you might try: Is the bug reproducible in the latest development release of perl? (5.15.7 I think). The easiest way to compile and install a dev release of perl is with perlbrew. Can you produce a minimal script that shows the bug that is as small as possible with a few dependencies as possible? Catalyst apps have a notoriously large number of dependences, so the perl maintainers won't enjoy digging through that mountain to find the module that is causing the trouble. The usual method is to start commenting out blocks of your code until you find the smallest script that will cause the bug.	[reply]
Re^4: Random corrupted double-linked list by ghenry (Vicar) on Feb 14, 2012 at 22:35 UTC
Re: Random corrupted double-linked list by ghenry (Vicar) on Feb 16, 2012 at 19:38 UTC
Looks like this was my issue with local::lib and perlbrew with XS things mixed between versions. Don't use local::lib, XS modules and different perlbrew perls! Walking the road to enlightenment... I found a penguin and a camel on the way..... Fancy a yourname@perl.me.uk? Just ask!!!	[reply]


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