From: Aaron Patterson <aaron@...>
Date: 2011-07-06T06:56:09+09:00
Subject: [ruby-core:37813] Re: [Ruby 1.9 - Bug #4962][Open] come back gem_prelude!


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On Sat, Jul 02, 2011 at 02:18:35PM +0900, Yusuke Endoh wrote:
>=20
> Issue #4962 has been reported by Yusuke Endoh.
>=20
> ----------------------------------------
> Bug #4962: come back gem_prelude!
> http://redmine.ruby-lang.org/issues/4962
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> Author: Yusuke Endoh
> Status: Open
> Priority: Normal
> Assignee: Eric Hodel
> Category: lib
> Target version: 1.9.3
> ruby -v: ruby 1.9.3dev (2011-07-01 trunk 32356) [i686-linux]
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>=20
> Hello, rubygems developers
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> Kosaki-san noticed that 1.9.3 is slower than 1.9.2 on many benchmarks.
> http://www.atdot.net/sp/view/5qunnl
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> I investigated and found that the cause is the lack of gem_prelude.rb.
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> Loading rubygems seems to create many objects and keep the references
> to them.  See below:
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>=20
> $ ruby -ve 'GC.start; p ObjectSpace.count_objects[:TOTAL]'
> ruby 1.9.2p180 (2011-02-18 revision 30909) [i686-linux]
> 9821
>=20
> $ ./ruby -ve 'GC.start; p ObjectSpace.count_objects[:TOTAL]'
> ruby 1.9.3dev (2011-07-01 trunk 32356) [i686-linux]
> 19638
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> $ ./ruby --disable-gems -ve 'GC.start; p ObjectSpace.count_objects[:TOTAL=
]'
> ruby 1.9.3dev (2011-07-01 trunk 32356) [i686-linux]
> 9821
>=20
>=20
> The number of live objects is proportional to the cost of GC mark phase.
> You can actually confirm the performance degradation with the following
> benchmark script:
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>   require 'tempfile'
>   max =3D 200_000
>   str =3D "Hello world!  " * 1000
>   f =3D Tempfile.new('yarv-benchmark')
>   f.write str
>   GC::Profiler.enable
>   max.times{
>     f.seek 0
>     f.read
>   }
>   p GC::Profiler.total_time
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>=20
> $ time ruby -v bm_io_file_read.rb
> ruby 1.9.2p180 (2011-02-18 revision 30909) [i686-linux]
> 0.7280460000000308
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> real    0m3.965s
> user    0m2.940s
> sys     0m1.024s
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> $ time ./ruby -v bm_io_file_read.rb
> ruby 1.9.3dev (2011-07-01 trunk 32356) [i686-linux]
> 1.396088000000029
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> real    0m4.786s
> user    0m3.716s
> sys     0m1.060s
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> $ time ./ruby --disable-gems -v bm_io_file_read.rb
> ruby 1.9.3dev (2011-07-01 trunk 32356) [i686-linux]
> 0.7640390000000309
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> real    0m4.079s
> user    0m2.872s
> sys     0m1.192s
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>=20
> The performance degradation can be seen by not only such micro benckmarks,
> but also my puzzle solvers :-(
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>=20
> There are some approaches to address the problem:
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>   1. to introduce a generational GC; this is impossible until 2.0 because
>      it requires modifications to all extension libraries.
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>   2. to diet rubygems; do not create any string, array, hash, and any
>      object as much as possible, and do not keep the references to them.
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>   3. to restore gem_prelude.rb to delay loading rubygems.

We can also help rbconfig go on a diet.  I know it's not enough, but
this eliminated ~400 object allocations on my machine.  (what is the
MAKEFILE_CONFIG for anyway?)

diff --git a/tool/mkconfig.rb b/tool/mkconfig.rb
index a2221f0..d78a347 100755
--- a/tool/mkconfig.rb
+++ b/tool/mkconfig.rb
@@ -202,8 +202,6 @@ print <<EOS
   CONFIG["vendorlibdir"] =3D "$(vendordir)/$(ruby_version)"
   CONFIG["vendorarchdir"] =3D "$(vendorlibdir)/$(sitearch)"
   CONFIG["topdir"] =3D File.dirname(__FILE__)
-  MAKEFILE_CONFIG =3D {}
-  CONFIG.each{|k,v| MAKEFILE_CONFIG[k] =3D v.dup}
   def RbConfig::expand(val, config =3D CONFIG)
     newval =3D val.gsub(/\\$\\$|\\$\\(([^()]+)\\)|\\$\\{([^{}]+)\\}/) {
       var =3D $&
@@ -233,6 +231,13 @@ print <<EOS
       RbConfig::CONFIG["ruby_install_name"] + RbConfig::CONFIG["EXEEXT"]
     )
   end
+
+  def self.const_missing const
+    return super unless :MAKEFILE_CONFIG =3D=3D const
+    const_set :MAKEFILE_CONFIG, {}
+    CONFIG.each{|k,v| MAKEFILE_CONFIG[k] =3D v.dup}
+    MAKEFILE_CONFIG
+  end
 end
 autoload :Config, "rbconfig/obsolete.rb" # compatibility for ruby-1.8.4 an=
d older.
 CROSS_COMPILING =3D nil unless defined? CROSS_COMPILING

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Aaron Patterson
http://tenderlovemaking.com/

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