Reblessing overloaded objects incurs significant performance penalty

[p5pRT]

Migrated from rt.perl.org#43283 (status was 'resolved')

Searchable as RT43283$

[p5pRT]

From rnorwood@redhat.com

This is a bug report for perl from rnorwood@​redhat.com,
generated with the help of perlbug 1.35 running under perl v5.8.8.

---

Apparently this change​:

http​://rt.perl.org/rt3//Public/Bug/Display.html?id=34925

Causes a significant performance hit for user's of Fedora's perl. This issue is in Red Hat's bugzilla here​:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=196836

The test script mentioned in comment #6​:

use Benchmark;
timethese(shift || 100000, {
'overload' => sub { push our @​array, TestOverload->new },
'not overload' => sub { push our @​array, TestNoverload->new },
});

package TestNoverload;
sub new { bless { hoge => 'hoge' }, shift }

package TestOverload;
use overload (
q{""} => sub {},
);
sub new { bless { hoge => 'hoge' }, shift }

Produces the following results on this system​:

<<EOQ
Benchmark​: timing 100000 iterations of not overload, overload...
not overload​: 1 wallclock secs ( 0.47 usr + 0.16 sys = 0.63 CPU) @​ 158730.16/s (n=100000)

  overload​: 962 wallclock secs (414.86 usr + 100.95 sys = 515.81 CPU) @​ 193.87/s (n=100000)
EOQ

Let me know if I can provide any assistance reproducing this problem.

---

---

Flags​:
  category=core
  severity=high

---

This perlbug was built using Perl v5.8.8 in the Red Hat build system.
It is being executed now by Perl v5.8.8 - Wed May 16 23​:22​:00 EDT 2007.

Site configuration information for perl v5.8.8​:

Configured by Red Hat, Inc. at Wed May 16 23​:22​:00 EDT 2007.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration​:
  Platform​:
  osname=linux, osvers=2.6.19-1.2895.fc6xen, archname=i386-linux-thread-multi
  uname='linux xenbuilder1.fedora.redhat.com 2.6.19-1.2895.fc6xen #1 smp wed jan 10 19​:09​:13 est 2007 i686 athlon i386 gnulinux '
  config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables -Dversion=5.8.8 -Dmyhostname=localhost -Dperladmin=root@​localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto -Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto -Ud_endservent_r_proto -Ud_setservent_r_proto -Dinc_version_list=5.8.7 5.8.6 5.8.5 -Dscriptdir=/usr/bin'
  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 -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
  optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables',
  cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -I/usr/include/gdbm'
  ccversion='', gccversion='4.1.2 20070502 (Red Hat 4.1.2-12)', 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=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
  perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
  libc=/lib/libc-2.6.so, so=so, useshrplib=true, libperl=libperl.so
  gnulibc_version='2.6'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE'
  cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables -L/usr/local/lib'

Locally applied patches​:
 

---

@​INC for perl v5.8.8​:
  /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi
  /usr/lib/perl5/site_perl/5.8.7/i386-linux-thread-multi
  /usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi
  /usr/lib/perl5/site_perl/5.8.5/i386-linux-thread-multi
  /usr/lib/perl5/site_perl/5.8.8
  /usr/lib/perl5/site_perl/5.8.7
  /usr/lib/perl5/site_perl/5.8.6
  /usr/lib/perl5/site_perl/5.8.5
  /usr/lib/perl5/site_perl
  /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi
  /usr/lib/perl5/vendor_perl/5.8.7/i386-linux-thread-multi
  /usr/lib/perl5/vendor_perl/5.8.6/i386-linux-thread-multi
  /usr/lib/perl5/vendor_perl/5.8.5/i386-linux-thread-multi
  /usr/lib/perl5/vendor_perl/5.8.8
  /usr/lib/perl5/vendor_perl/5.8.7
  /usr/lib/perl5/vendor_perl/5.8.6
  /usr/lib/perl5/vendor_perl/5.8.5
  /usr/lib/perl5/vendor_perl
  /usr/lib/perl5/5.8.8/i386-linux-thread-multi
  /usr/lib/perl5/5.8.8
  .

---

Environment for perl v5.8.8​:
  HOME=/root
  LANG=en_US.UTF-8
  LANGUAGE (unset)
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/usr/local/sbin​:/usr/local/bin​:/sbin​:/bin​:/usr/sbin​:/usr/bin​:/root/bin
  PERL_BADLANG (unset)
  SHELL=/bin/bash

[p5pRT]

From @nwc10

On Thu, Jun 21, 2007 at 01​:14​:46PM -0700, Robin Norwood wrote​:

-----------------------------------------------------------------
Apparently this change​:

http​://rt.perl.org/rt3//Public/Bug/Display.html?id=34925

Causes a significant performance hit for user's of Fedora's perl. This issue is in Red Hat's bugzilla here​:

That change (27512) postdates the release of 5.8.8
I thought that it was fixed with change 28775.
Has that been integrated to Fedora's perl?

http​://public.activestate.com/cgi-bin/perlbrowse?patch_num=28775&show_patch=Show+Patch

Change 28775 by nicholas@​nicholas-saigo on 2006/09/02 16​:01​:36

  Integrate​:
  [ 28771]
  Change the generation of {} and [] from 3 ops to 1, and avoid 1 mortal
  on the tempstack, by augmenting pp_anonlist and pp_anonhash to accept
  OPf_SPECIAL to mean "return a reference to the aggregate" on the stack
  rather than the aggregate itself.

Nicholas Clark

[p5pRT]

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

[p5pRT]

From rnorwood@redhat.com

"Nicholas Clark via RT" <perlbug-followup@​perl.org> writes​:

On Thu, Jun 21, 2007 at 01​:14​:46PM -0700, Robin Norwood wrote​:

-----------------------------------------------------------------
Apparently this change​:

http​://rt.perl.org/rt3//Public/Bug/Display.html?id=34925

Causes a significant performance hit for user's of Fedora's perl. This issue is in Red Hat's bugzilla here​:

That change (27512) postdates the release of 5.8.8
I thought that it was fixed with change 28775.
Has that been integrated to Fedora's perl?

http​://public.activestate.com/cgi-bin/perlbrowse?patch_num=28775&show_patch=Show+Patch

Yep, it looks like we took the 27512 patch and neglected the 28775
patch. I'll build another perl with that patch and let you know what I
see.

Thanks!

-RN

Change 28775 by nicholas@​nicholas-saigo on 2006/09/02 16​:01​:36

Integrate​:
\[ 28771\]
Change the generation of \{\} and \[\] from 3 ops to 1\, and avoid 1 mortal
on the tempstack\, by augmenting pp\_anonlist and pp\_anonhash to accept
OPf\_SPECIAL to mean "return a reference to the aggregate" on the stack
rather than the aggregate itself\.

Nicholas Clark

--
Robin Norwood
Red Hat, Inc.

"The Sage does nothing, yet nothing remains undone."
-Lao Tzu, Te Tao Ching

[p5pRT]

From rnorwood@redhat.com

Hi,

A patch derived from change #28775 fixes the problem on my test system.
I'll apply it to Fedora's perl. Thanks for your help.

-RN

--
Robin Norwood
Red Hat, Inc.

"The Sage does nothing, yet nothing remains undone."
-Lao Tzu, Te Tao Ching

[p5pRT]

p5p@spam.wizbit.be - Status changed from 'open' to 'resolved'