Memleak in Perl_sv_grow in 5.16+

[p5pRT]

Migrated from rt.perl.org#115738 (status was 'rejected')

Searchable as RT115738$

[p5pRT]

From @vovkasm

This fragment is the constant growth of memory (this reduced showcase
from Hash​::Merge code)​:

while (1) {
  my $o = bless {}, 'main';
  test({});
  $o->test;
}
sub test { &test2; }
sub test2 { ref($_[0]) && eval { $_[0]->isa(__PACKAGE__) }; }

If I change "while" to "for (1..100)" and run with valgrind then I got this​:
==29948== 1,584 bytes in 99 blocks are definitely lost in loss record 238 of 263
==29948== at 0x4C2B3F8​: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==29948== by 0x478CF4​: Perl_safesysmalloc (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x4A71ED​: Perl_sv_grow (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x4A84CF​: Perl_sv_setpv (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x4A2FA1​: Perl_sv_ref (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x4B0B19​: Perl_pp_ref (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x493A02​: Perl_runops_standard (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x439F4F​: perl_run (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)
==29948== by 0x41F34C​: main (in
/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin/perl)

* bug exists​: threaded and nonthreaded perls versions 5.16.1 and 5.16.2
* bug not exists​: nonthreaded 5.14.2

one of my perl -V output​:
Summary of my perl5 (revision 5 version 16 subversion 1) configuration​:

  Platform​:
  osname=linux, osvers=3.2.0-31-generic, archname=x86_64-linux
  uname='linux vovkasm-wrk 3.2.0-31-generic #50-ubuntu smp fri sep 7
16​:16​:45 utc 2012 x86_64 x86_64 x86_64 gnulinux '
  config_args='-de
-Dprefix=/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads
-Uusethreads'
  hint=recommended, useposix=true, d_sigaction=define
  useithreads=undef, usemultiplicity=undef
  useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
  use64bitint=define, use64bitall=define, uselongdouble=undef
  usemymalloc=n, bincompat5005=undef
  Compiler​:
  cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector
-I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
  optimize='-O2',
  cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
  ccversion='', gccversion='4.6.3', 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 =' -fstack-protector -L/usr/local/lib'
  libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib
/usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
  libs=-lnsl -lgdbm -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
  perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
  libc=, so=so, useshrplib=false, libperl=libperl.a
  gnulibc_version='2.15'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
  cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
-fstack-protector'

Characteristics of this binary (from libperl)​:
  Compile-time options​: HAS_TIMES PERLIO_LAYERS PERL_DONT_CREATE_GVSV
  PERL_MALLOC_WRAP PERL_PRESERVE_IVUV USE_64_BIT_ALL
  USE_64_BIT_INT USE_LARGE_FILES USE_LOCALE
  USE_LOCALE_COLLATE USE_LOCALE_CTYPE
  USE_LOCALE_NUMERIC USE_PERLIO USE_PERL_ATOF
  Built under linux
  Compiled at Sep 10 2012 16​:06​:36
  %ENV​:
  PERLBREW_BASHRC_VERSION="0.43"
  PERLBREW_HOME="/home/vovkasm/.perlbrew"
  PERLBREW_MANPATH="/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/man"
  PERLBREW_PATH="/home/vovkasm/perl5/perlbrew/bin​:/home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/bin"
  PERLBREW_PERL="perl-5.16.1-nothreads"
  PERLBREW_ROOT="/home/vovkasm/perl5/perlbrew"
  PERLBREW_VERSION="0.43"
  @​INC​:
  /home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/lib/site_perl/5.16.1/x86_64-linux
  /home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/lib/site_perl/5.16.1
  /home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/lib/5.16.1/x86_64-linux
  /home/vovkasm/perl5/perlbrew/perls/perl-5.16.1-nothreads/lib/5.16.1
  .

--
Vladimir Timofeev <vovkasm@​gmail.com>

[p5pRT]

From @cpansprout

On Thu Nov 15 00​:05​:57 2012, vovkasm wrote​:

This fragment is the constant growth of memory (this reduced showcase
from Hash​::Merge code)​:

while (1) {
my $o = bless {}, 'main';
test({});
$o->test;
}
sub test { &test2; }
sub test2 { ref($_[0]) && eval { $_[0]->isa(__PACKAGE__) }; }

The leak seems to have disappeared somewhere between 7e2a0d4 and
39984de, but I don’t know exactly which commit is responsible.

--

Father Chrysostomos

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From @jkeenan

On Thu Nov 15 06​:11​:23 2012, sprout wrote​:

On Thu Nov 15 00​:05​:57 2012, vovkasm wrote​:

This fragment is the constant growth of memory (this reduced showcase
from Hash​::Merge code)​:

while (1) {
my $o = bless {}, 'main';
test({});
$o->test;
}
sub test { &test2; }
sub test2 { ref($_[0]) && eval { $_[0]->isa(__PACKAGE__) }; }

The leak seems to have disappeared somewhere between 7e2a0d4 and
39984de, but I don’t know exactly which commit is responsible.

I read Father C's comment to mean that the problem has been resolved. Since there has been no further correspondence in this ticket in more than a year, I am closing this ticket.

Thank you very much.
Jim Keenan

[p5pRT]

@jkeenan - Status changed from 'open' to 'rejected'