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Id: 69598
Status: resolved
Priority: 0/
Queue: perl5

Owner: Nobody
Requestors: jasonmbaumgartner [at]

Operating System: Linux
PatchStatus: (no value)
Severity: High
Perl Version: 5.10.0
Fixed In: 5.13.5

Subject: Memory Leak with Threads
Date: Tue, 6 Oct 2009 15:20:15 +0000
To: perlbug [...]
From: Jason Baumgartner <jasonmbaumgartner [...]>
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This is a bug report for perl from, generated with the help of perlbug 1.36 running under perl 5.10.0. ----------------------------------------------------------------- [Please enter your report here] The following script leaks memory. Bug appears to also affect others on the site Perlmonks. Please visit for more versions that this bug affects. Sample code to reproduce bug: #!/usr/bin/perl use Thread; use Time::HiRes qw(usleep); while(usleep(100)) { my $thr1 = new Thread \&doNothing; $thr1->join; } sub doNothing {} [Please do not change anything below this line] ----------------------------------------------------------------- --- Flags: category=core severity=high --- Site configuration information for perl 5.10.0: Configured by Debian Project at Fri Jun 26 18:43:11 UTC 2009. Summary of my perl5 (revision 5 version 10 subversion 0) configuration: Platform: osname=linux, osvers=2.6.24-23-server, archname=i486-linux-gnu-thread-multi uname='linux rothera 2.6.24-23-server #1 smp wed apr 1 22:22:14 utc 2009 i686 gnulinux ' config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/sh$ hint=recommended, useposix=true, d_sigaction=define 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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64', optimize='-O2 -g', cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include' ccversion='', gccversion='4.3.3', 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='cc', ldflags =' -L/usr/local/lib' libpth=/usr/local/lib /lib /usr/lib /usr/lib64 libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt perllibs=-ldl -lm -lpthread -lc -lcrypt libc=/lib/, so=so, useshrplib=true, gnulibc_version='2.9' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E' cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib' Locally applied patches: --- @INC for perl 5.10.0: /etc/perl /usr/local/lib/perl/5.10.0 /usr/local/share/perl/5.10.0 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl . --- Environment for perl 5.10.0: HOME=/home/jbaumgartner LANG=en_US.UTF-8 LANGUAGE (unset) LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games PERL_BADLANG (unset) SHELL=/bin/bash
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> The following script leaks memory.
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> use Thread;
G'day Jason Baumgartner. Thanks for spotting this, it's certainly an interesting leak of scope. While we're working on this, you may want to investigate the threads and threads::shared modules which take advantage of the new Perl threads model. Thanks again, Jacinta
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On Wed Nov 11 01:47:37 2009, jarich wrote: Show quoted text
> While we're working on this, you may want to investigate the threads and > threads::shared modules which take advantage of the new Perl threads
model. There's no difference which module to use, the following sample leaking memory. Tested on Ubuntu 9.04 with perl-5.10.0 and on Ubuntu 9.10 with 5.10.0, 5.10.1, and 5.11.2. use strict; use warnings; use threads; use Time::HiRes qw(usleep); my $count = 0; while( 1 ) { usleep(100); my $thr1 = threads->create( \&doNothing ); $thr1->join; unless( ++$count % 1000 ) { # prints RSS printf "%3d: %s\n", $count, ( split /\s+/, qx[ps vhp $$] )[ 7 ]; } } sub doNothing { 1 }
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> > The following script leaks memory.
This simplified sample leaks memory in Linux but not in Windows! Tested with 5.10.0 and 5.10.1 which was locally compiled from CPAN source. use threads; threads->create(sub {})->join while 1;
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This appears to leak only on none-debugging builds, and appears to have been fixed sometime between 5.13.4 and 5.13.5

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