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[perl #27085] segfault when using a shared hash ref with ithreads
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From:
Stas Bekman
Date:
February 24, 2004 20:31
Subject:
[perl #27085] segfault when using a shared hash ref with ithreads
Message ID:
rt-3.0.8-27085-79876.14.3992251373196@perl.org
# New Ticket Created by Stas Bekman
# Please include the string: [perl #27085]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=27085 >
This is a bug report for perl from stas@rabbit.stason.org,
generated with the help of perlbug 1.34 running under perl v5.8.3.
-----------------------------------------------------------------
[Please enter your report here]
The following program segfaults:
#foo
package My::InterpreterCounter;
use strict;
use warnings FATAL => 'all';
use threads;
use threads::shared;
my $obj = My::InterpreterCounter->new();
my $ctr = &share({});
$ctr->{cnt} = 1;
sub new {
my $class = shift;
my $self = 0;
return bless \$self, $class;
}
sub CLONE {
print "CLONE\n";
$$obj = 1;
}
sub DESTROY {
print "DESTROY\n";
lock $ctr;
$ctr->{cnt}--;
}
sub END {
print "END\n";
# DESTROY object now before $ctr went out of scope
#undef $obj;
}
__END__
% perl foo
END
DESTROY
Segmentation fault
gdb) where
#0 0x403aabd6 in sharedsv_elem_mg_FETCH ()
from
/usr/lib/perl5/5.8.3/i386-linux-thread-multi/auto/threads/shared/shared.so
#1 0x00000001 in ?? ()
#2 0x4013bb78 in ?? ()
from /usr/lib/perl5/5.8.3/i386-linux-thread-multi/CORE/libperl.so
#3 0x00000050 in ?? ()
sorry, that perl has no debug built.
the following tweaks make the segfault go away:
1. comment out #$$obj = 1; in CLONE
- I suppose this $$obj was creating a closure (which is not a fault of my
program), in fact it can be any subroutine, not just CLONE. so $obj was
not destroyed before the END block is run. But after the END block is
called a shared $ctr has been destroyed, so the late DESTROY causes a
segfault. Indeed doing this comment out, changes the order:
% perl foo
DESTROY
END
and the segfault goes away.
2. explicitly destroy $obj from the END block
the segfault goes away
3. change the definition of the shared var to:
my $ctr : shared = &share({});
4. use a different perl. The segfault I have is with 5.8.3 from mandrake,
I don't have it with 5.8.3 that I've built on my own. Here is what seems
to be the interesting differences:
- cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
- optimize='-O2 -fomit-frame-pointer -pipe -march=i586 -mcpu=pentiumpro
',
- cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
+ cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-DDEBUGGING -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
+ optimize='-g',
+ cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING
-fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.3.2 (Mandrake Linux 10.0 3.3.2-4mdk)',
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
- ld='gcc', ldflags =' -L/usr/local/lib'
+ ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
- libs=-lnsl -lndbm -lgdbm -ldl -lm -lcrypt -lutil -lpthread -lc
+ libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
- libc=/lib/libc-2.3.3.so, so=so, useshrplib=true, libperl=libperl.so
- gnulibc_version='2.3.3'
+ libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so
+ gnulibc_version='2.3.2'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic
-Wl,-rpath,/usr/lib/perl5/5.8.3/i386-linux-thread-multi/CORE'
- cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
+ cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=low
---
Site configuration information for perl v5.8.3:
Configured by pixel at Tue Feb 3 13:48:38 CET 2004.
Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
Platform:
osname=linux, osvers=2.6.0-1mdkenterprise, archname=i386-linux-thread-multi
uname='linux no.mandrakesoft.com 2.6.0-1mdkenterprise #1 smp thu dec 18
16:11:28 est 2003 i686 unknown unknown gnulinux '
config_args='-des -Dinc_version_list=5.8.2/i386-linux-thread-multi 5.8.2
5.8.1/i386-linux-thread-multi 5.8.1 5.8.0/i386-linux-thread-multi 5.8.0 5.6.1
5.6.0 -Darchname=i386-linux -Dcc=gcc -Doptimize=-O2 -fomit-frame-pointer -pipe
-march=i586 -mcpu=pentiumpro -Dprefix=/usr -Dvendorprefix=/usr
-Dsiteprefix=/usr -Dman3ext=3pm -Dcf_by=MandrakeSoft -Dmyhostname=localhost
-Dperladmin=root@localhost -Dd_dosuid -Ud_csh -Duseshrplib -Dusethreads'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define
usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
optimize='-O2 -fomit-frame-pointer -pipe -march=i586 -mcpu=pentiumpro ',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.3.2 (Mandrake Linux 10.0 3.3.2-4mdk)',
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='gcc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lndbm -lgdbm -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=/lib/libc-2.3.3.so, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.3'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic
-Wl,-rpath,/usr/lib/perl5/5.8.3/i386-linux-thread-multi/CORE'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.8.3:
/usr/lib/perl5/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/5.8.3
/usr/lib/perl5/site_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.3
/usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.1
/usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.3
/usr/lib/perl5/vendor_perl/5.8.2/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.2
/usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.1
/usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.0
/usr/lib/perl5/vendor_perl
.
---
Environment for perl v5.8.3:
HOME=/home/stas
LANG=en_GB
LANGUAGE=en_GB:en
LC_ADDRESS=en_CA
LC_COLLATE=en_GB
LC_CTYPE=en_GB
LC_IDENTIFICATION=en_CA
LC_MEASUREMENT=en_CA
LC_MESSAGES=en_GB
LC_MONETARY=en_CA
LC_NAME=en_CA
LC_NUMERIC=en_CA
LC_PAPER=en_CA
LC_TELEPHONE=en_CA
LC_TIME=en_GB
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/usr//bin:/bin:/usr/bin:.:/usr/local/bin:/usr/X11R6/bin/:/usr/games:/home/stas/bin:/home/stas/bin:/usr/local/bin:/usr/X11R6/bin:/usr/java/j2re1.4.0/bin/
PERLDOC_PAGER=less -R
PERL_BADLANG (unset)
SHELL=/bin/tcsh
--
__________________________________________________________________
Stas Bekman JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide ---> http://perl.apache.org
mailto:stas@stason.org http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org http://ticketmaster.com
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[perl #27085] segfault when using a shared hash ref with ithreads
by Stas Bekman