From: "charliesome (Charlie Somerville)" <charliesome@...>
Date: 2013-12-03T12:27:19+09:00
Subject: [ruby-core:58822] [ruby-trunk - Bug #9203] fstring_table size and	performance


Issue #9203 has been updated by charliesome (Charlie Somerville).


It looks like this is a problem with RGenGC.

I can reproduce the performance issue with the script you posted:

    �� ./rb x.rb
           user     system      total        real
      16.360000   0.600000  16.960000 ( 16.960314)
      19.370000   0.560000  19.930000 ( 19.938043)
      28.650000   0.780000  29.430000 ( 29.436909)

However if I put GC.start before each x.report line, it fixes the performance issue:

    �� ./rb x.rb
           user     system      total        real
      16.650000   0.620000  17.270000 ( 17.263282)
      14.830000   0.280000  15.110000 ( 15.116170)
      14.950000   0.280000  15.230000 ( 15.225395)

----------------------------------------
Bug #9203: fstring_table size and performance
https://bugs.ruby-lang.org/issues/9203#change-43385

Author: ko1 (Koichi Sasada)
Status: Open
Priority: Normal
Assignee: charliesome (Charlie Somerville)
Category: core
Target version: current: 2.1.0
ruby -v: 2.1
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Clip question discussed on skype.

I have two questions about the following benchmark and result.

(1) why slowdown if seq == true ?
(2) why not GC'ed? (fatal error)

###

require 'benchmark'
a = 0
b = n = 10_000_000
seq = true

Benchmark.bm{|x|
  x.report{
    h = {}
    (a..b).each{|i|
      h[i.to_s] = nil
    }
  }
  a, b = b, b+n if seq
  x.report{
    h = {}
    (a..b).each{|i|
      h[i.to_s] = nil
    }
  }
  a, b = b, b+n if seq
  x.report{
    h = {}
    (a..b).each{|i|
      h[i.to_s] = nil
    }
  }
}

__END__
seq == false
ruby 2.1.0dev (2013-12-02 trunk 43956) [i386-mswin32_110]
       user     system      total        real
  18.720000   0.062000  18.782000 ( 18.854394)
  15.460000   0.110000  15.570000 ( 15.569977)
  15.366000   0.093000  15.459000 ( 15.481966)

ruby 2.0.0p317 (2013-09-15 revision 42947) [i386-mswin32_110]
       user     system      total        real
  14.789000   0.094000  14.883000 ( 14.890891)
  15.319000   0.078000  15.397000 ( 15.421958)
  15.272000   0.078000  15.350000 ( 15.351450)

seq == true
ruby 2.1.0dev (2013-12-02 trunk 43956) [i386-mswin32_110]
       user     system      total        real
  18.689000   0.187000  18.876000 ( 18.934904)
  27.612000   0.250000  27.862000 ( 27.940048)
 [FATAL] failed to allocate memory

ruby 2.1.0dev (2013-12-02 trunk 43956) [i686-linux]
       user     system      total        real
  22.220000   0.400000  22.620000 ( 22.617157)
  34.170000   0.130000  34.300000 ( 34.298706)
  43.170000   0.110000  43.280000 ( 43.277328)

ruby 2.0.0p317 (2013-09-15 revision 42947) [i386-mswin32_110]
       user     system      total        real
  14.758000   0.094000  14.852000 ( 14.892891)
  15.506000   0.047000  15.553000 ( 15.566477)
  15.523000   0.015000  15.538000 ( 15.560976)



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