[perl #59516] Memory leak with regex in 5.10.0

["robin.hill@biowisdom.com (via RT)" <perlbug-followup@perl.org>]

# New Ticket Created by  robin.hill@biowisdom.com 
# Please include the string:  [perl #59516]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=59516 >



This is a bug report for perl from robin.hill@biowisdom.com,
generated with the help of perlbug 1.36 running under perl 5.10.0.


-----------------------------------------------------------------
I've been having problems with a script consuming all memory on
the system and have tracked this down to the regex.  The problem
only seems to occur with a combination of quoted variables and
singular character classes.

The following example script steadily increases in memory usage
while running:

#########################################################
#!/usr/bin/perl -w

use strict;
use warnings;
use Time::HiRes qw(usleep);

my $text = 'Test string';

for my $str (1..10000) {
    my ($res) = $text =~ /\Q$str\E[a][b][c][d][e][f]/;
    usleep(5);
}
#########################################################

Changing the character classes to include more than one character
appears to eliminate the leak. (In the actual script I'm trying to
check for brackets and following the recommendation of using singular
character classes instead of escaping the metacharacter).


[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
This perlbug was built using Perl 5.10.0 - Tue Jul 15 14:37:49 UTC 2008
It is being executed now by  Perl 5.10.0 - Tue Jul 15 14:31:57 UTC 2008.

Site configuration information for perl 5.10.0:

Configured by abuild at Tue Jul 15 14:31:57 UTC 2008.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.25, archname=x86_64-linux-thread-multi
    uname='linux stravinsky 2.6.25 #1 smp 20080210 20:01:04 utc x86_64 x86_64 x86_64 gnulinux '
    config_args='-ds -e -Dprefix=/usr -Dvendorprefix=/usr -Dinstallusrbinperl -Dusethreads -Di_db -Di_dbm -Di_ndbm -Di_gdbm -Duseshrplib=true -Doptimize=-O2 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -g -Wall -pipe -Accflags=-DPERL_USE_SAFE_PUTENV'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DPERL_USE_SAFE_PUTENV -DDEBUGGING -fno-strict-aliasing -pipe -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -g -Wall -pipe',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DPERL_USE_SAFE_PUTENV -DDEBUGGING -fno-strict-aliasing -pipe'
    ccversion='', gccversion='4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036]', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib64'
    libpth=/lib64 /usr/lib64 /usr/local/lib64
    libs=-lm -ldl -lcrypt -lpthread
    perllibs=-lm -ldl -lcrypt -lpthread
    libc=/lib64/libc-2.8.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.8'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.10.0/x86_64-linux-thread-multi/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib64'

Locally applied patches:
    

---
@INC for perl 5.10.0:
    /home/hillrobi/svn/perl_scripts
    /home/hillrobi/svn/perl_scripts
    /home/hillrobi/svn/perl_scripts
    /usr/lib/perl5/5.10.0/x86_64-linux-thread-multi
    /usr/lib/perl5/5.10.0
    /usr/lib/perl5/site_perl/5.10.0/x86_64-linux-thread-multi
    /usr/lib/perl5/site_perl/5.10.0
    /usr/lib/perl5/vendor_perl/5.10.0/x86_64-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.10.0
    /usr/lib/perl5/vendor_perl
    .

---
Environment for perl 5.10.0:
    HOME=/home/hillrobi
    LANG=en_GB.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/opt/oracle/OraHome1/lib:/opt/oracle/OraHome1/ctx/lib:/opt/oracle/OraHome1/lib32
    LOGDIR (unset)
    PATH=/home/hillrobi/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/games:/usr/lib/mit/bin:/usr/lib/mit/sbin:/opt/oracle/OraHome1/bin:/usr/local/bin:/home/hillrobi/bin
    PERL5LIB=/home/hillrobi/svn/perl_scripts:/home/hillrobi/svn/perl_scripts:/home/hillrobi/svn/perl_scripts
    PERL_BADLANG (unset)
    SHELL=/bin/bash

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Follow-Ups from:

Dave Mitchell <davem@iabyn.com>

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