MRI Ruby和jRuby之间的性能差异

Question

在做一些基准测试以回答有关连接数组的最快方法的 this问题时,我很惊讶当我使用jRuby进行相同的基准测试时,测试速度要慢得多.

这是否意味着关于jRuby比MRI Ruby更快的旧的慢板已经消失了？或者这是关于如何在jRuby中处理数组？

这里的基准测试和MRI Ruby 2.3.0和jRuby 9.1.2.0的结果
两者都运行在64位Windows 7机箱上,所有4个处理器都占用50-60％,内存使用率为±5.5GB.必须使用参数-J-Xmx1500M启动jRuby以提供足够的堆空间.由于堆栈级别太深,我不得不使用push删除测试,并且还删除了最慢的方法,使测试时间不长.使用Jave运行时：1.7.0_21

require 'Benchmark'
N = 100

class Array
  def concat_all 
    self.reduce([],:+)
  end
end

# small arrays
a = (1..10).to_a
b = (11..20).to_a
c = (21..30).to_a

Benchmark.bm do |r|
  r.report('plus       ')  { N.times { a + b + c }}
  r.report('concat     ') { N.times { [].concat(a).concat(b).concat(c) }}
  r.report('splash     ') { N.times {[*a,*b,*c]} }
  r.report('concat_all ')  { N.times { [a,b,c].concat_all }}
  r.report('flat_map   ') { N.times {[a,c].flat_map(&:itself)} }
end

#large arrays
a = (1..10_000_000).to_a
b = (10_000_001..20_000_000).to_a
c = (20_000_001..30_000_000).to_a

Benchmark.bm do |r|
  r.report('plus       ')  { N.times { a + b + c }}
  r.report('concat     ') { N.times { [].concat(a).concat(b).concat(c) }}
  r.report('splash     ') { N.times {[*a,c].flat_map(&:itself)} }
end

这个问题与使用的不同方法无关,请参阅原始问题.
在这两种情况下,MRI都快7倍！
有人能解释我为什么？
我也很好奇其他实现如何,比如RBX(Rubinius)

C:Users...>d:jrubybinjruby -J-Xmx1500M concat3.rb
       user     system      total        real
plus         0.000000   0.000000   0.000000 (  0.000946)
concat       0.000000   0.000000   0.000000 (  0.001436)
splash       0.000000   0.000000   0.000000 (  0.001456)
concat_all   0.000000   0.000000   0.000000 (  0.002177)
flat_map  0.010000   0.000000   0.010000 (  0.003179)
       user     system      total        real
plus       140.166000   0.000000 140.166000 (140.158687)
concat     143.475000   0.000000 143.475000 (143.473786)
splash     139.408000   0.000000 139.408000 (139.406671)
concat_all 144.475000   0.000000 144.475000 (144.474436)
flat_map143.519000   0.000000 143.519000 (143.517636)

C:Users...>ruby concat3.rb
       user     system      total        real
plus         0.000000   0.000000   0.000000 (  0.000074)
concat       0.000000   0.000000   0.000000 (  0.000065)
splash       0.000000   0.000000   0.000000 (  0.000098)
concat_all   0.000000   0.000000   0.000000 (  0.000141)
flat_map     0.000000   0.000000   0.000000 (  0.000122)
       user     system      total        real
plus        15.226000   6.723000  21.949000 ( 21.958854)
concat      11.700000   9.142000  20.842000 ( 20.928087)
splash      21.247000  12.589000  33.836000 ( 33.933170)
concat_all  14.508000   8.315000  22.823000 ( 22.871641)
flat_map    11.170000   8.923000  20.093000 ( 20.170945)

Answer 1

一般规则是(如评论中所述)JRuby / JVM需要预热.

通常bmbm是合适的,虽然TIMES = 1000应该增加(至少对于小阵列情况),1.5G可能还不足以实现JRuby的最佳性能(注意到从-Xmx2g到-Xmx3g的数量发生了相当大的变化) .这是结果：

ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ruby concat3.rb
Rehearsal -----------------------------------------------
plus          0.000000   0.000000   0.000000 (  0.000076)
concat        0.000000   0.000000   0.000000 (  0.000070)
splash        0.000000   0.000000   0.000000 (  0.000099)
concat_all    0.000000   0.000000   0.000000 (  0.000136)
flat_map      0.000000   0.000000   0.000000 (  0.000138)
-------------------------------------- total: 0.000000sec

                  user     system      total        real
plus          0.000000   0.000000   0.000000 (  0.000051)
concat        0.000000   0.000000   0.000000 (  0.000059)
splash        0.000000   0.000000   0.000000 (  0.000083)
concat_all    0.000000   0.000000   0.000000 (  0.000120)
flat_map      0.000000   0.000000   0.000000 (  0.000173)
Rehearsal -----------------------------------------------
plus         43.040000   3.320000  46.360000 ( 46.351004)
concat       15.080000   3.870000  18.950000 ( 19.228059)
splash       49.680000   4.820000  54.500000 ( 54.587707)
concat_all   51.840000   5.260000  57.100000 ( 57.114867)
flat_map     17.380000   5.340000  22.720000 ( 22.716987)
------------------------------------ total: 199.630000sec

                  user     system      total        real
plus         42.880000   3.600000  46.480000 ( 46.506013)
concat       17.230000   5.290000  22.520000 ( 22.890809)
splash       60.300000   7.480000  67.780000 ( 67.878534)
concat_all   54.910000   6.480000  61.390000 ( 61.404383)
flat_map     17.310000   5.570000  22.880000 ( 23.223789)

…


……所以看起来恰恰相反–MRI 2.3比JRuby 9.1慢2-5倍


jruby 9.1.6.0 (2.3.1) 2016-11-09 0150a76 Java HotSpot(TM) 64-Bit Server VM 25.112-b15 on 1.8.0_112-b15 +jit [linux-x86_64]

$jruby -J-Xmx3g concat3.rb
Rehearsal -----------------------------------------------
plus          0.010000   0.000000   0.010000 (  0.001445)
concat        0.000000   0.000000   0.000000 (  0.002534)
splash        0.000000   0.000000   0.000000 (  0.001791)
concat_all    0.000000   0.000000   0.000000 (  0.002513)
flat_map      0.010000   0.000000   0.010000 (  0.007088)
-------------------------------------- total: 0.020000sec

                  user     system      total        real
plus          0.010000   0.000000   0.010000 (  0.002700)
concat        0.000000   0.000000   0.000000 (  0.001085)
splash        0.000000   0.000000   0.000000 (  0.001569)
concat_all    0.000000   0.000000   0.000000 (  0.003052)
flat_map      0.000000   0.000000   0.000000 (  0.002252)
Rehearsal -----------------------------------------------
plus         32.410000   0.670000  33.080000 ( 17.385688)
concat       18.610000   0.ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ruby concat3.rb
Rehearsal -----------------------------------------------
plus          0.000000   0.000000   0.000000 (  0.000076)
concat        0.000000   0.000000   0.000000 (  0.000070)
splash        0.000000   0.000000   0.000000 (  0.000099)
concat_all    0.000000   0.000000   0.000000 (  0.000136)
flat_map      0.000000   0.000000   0.000000 (  0.000138)
-------------------------------------- total: 0.000000sec

                  user     system      total        real
plus          0.000000   0.000000   0.000000 (  0.000051)
concat        0.000000   0.000000   0.000000 (  0.000059)
splash        0.000000   0.000000   0.000000 (  0.000083)
concat_all    0.000000   0.000000   0.000000 (  0.000120)
flat_map      0.000000   0.000000   0.000000 (  0.000173)
Rehearsal -----------------------------------------------
plus         43.040000   3.320000  46.360000 ( 46.351004)
concat       15.080000   3.870000  18.950000 ( 19.228059)
splash       49.680000   4.820000  54.500000 ( 54.587707)
concat_all   51.840000   5.260000  57.100000 ( 57.114867)
flat_map     17.380000   5.340000  22.720000 ( 22.716987)
------------------------------------ total: 199.630000sec

                  user     system      total        real
plus         42.880000   3.600000  46.480000 ( 46.506013)
concat       17.230000   5.290000  22.520000 ( 22.890809)
splash       60.300000   7.480000  67.780000 ( 67.878534)
concat_all   54.910000   6.480000  61.390000 ( 61.404383)
flat_map     17.310000   5.570000  22.880000 ( 23.223789)

0 18.670000 ( 11.206419)
 splash 57.770000 0.330000 58.100000 ( 25.366032)
 concat_all 19.100000 0.030000 19.130000 ( 13.747319)
 flat_map 16.160000 0.040000 16.200000 ( 10.534130)
 ------------------------------------ total: 145.180000sec
 user system total real
 plus 16.
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ruby concat3.rb
Rehearsal -----------------------------------------------
plus          0.000000   0.000000   0.000000 (  0.000076)
concat        0.000000   0.000000   0.000000 (  0.000070)
splash        0.000000   0.000000   0.000000 (  0.000099)
concat_all    0.000000   0.000000   0.000000 (  0.000136)
flat_map      0.000000   0.000000   0.000000 (  0.000138)
-------------------------------------- total: 0.000000sec

                  user     system      total        real
plus          0.000000   0.000000   0.000000 (  0.000051)
concat        0.000000   0.000000   0.000000 (  0.000059)
splash        0.000000   0.000000   0.000000 (  0.000083)
concat_all    0.000000   0.000000   0.000000 (  0.000120)
flat_map      0.000000   0.000000   0.000000 (  0.000173)
Rehearsal -----------------------------------------------
plus         43.040000   3.320000  46.360000 ( 46.351004)
concat       15.080000   3.870000  18.950000 ( 19.228059)
splash       49.680000   4.820000  54.500000 ( 54.587707)
concat_all   51.840000   5.260000  57.100000 ( 57.114867)
flat_map     17.380000   5.340000  22.720000 ( 22.716987)
------------------------------------ total: 199.630000sec

                  user     system      total        real
plus         42.880000   3.600000  46.480000 ( 46.506013)
concat       17.230000   5.290000  22.520000 ( 22.890809)
splash       60.300000   7.480000  67.780000 ( 67.878534)
concat_all   54.910000   6.480000  61.390000 ( 61.404383)
flat_map     17.310000   5.570000  22.880000 ( 23.223789)
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ruby concat3.rb
Rehearsal -----------------------------------------------
plus          0.000000   0.000000   0.000000 (  0.000076)
concat        0.000000   0.000000   0.000000 (  0.000070)
splash        0.000000   0.000000   0.000000 (  0.000099)
concat_all    0.000000   0.000000   0.000000 (  0.000136)
flat_map      0.000000   0.000000   0.000000 (  0.000138)
-------------------------------------- total: 0.000000sec

                  user     system      total        real
plus          0.000000   0.000000   0.000000 (  0.000051)
concat        0.000000   0.000000   0.000000 (  0.000059)
splash        0.000000   0.000000   0.000000 (  0.000083)
concat_all    0.000000   0.000000   0.000000 (  0.000120)
flat_map      0.000000   0.000000   0.000000 (  0.000173)
Rehearsal -----------------------------------------------
plus         43.040000   3.320000  46.360000 ( 46.351004)
concat       15.080000   3.870000  18.950000 ( 19.228059)
splash       49.680000   4.820000  54.500000 ( 54.587707)
concat_all   51.840000   5.260000  57.100000 ( 57.114867)
flat_map     17.380000   5.340000  22.720000 ( 22.716987)
------------------------------------ total: 199.630000sec

                  user     system      total        real
plus         42.880000   3.600000  46.480000 ( 46.506013)
concat       17.230000   5.290000  22.520000 ( 22.890809)
splash       60.300000   7.480000  67.780000 ( 67.878534)
concat_all   54.910000   6.480000  61.390000 ( 61.404383)
flat_map     17.310000   5.570000  22.880000 ( 23.223789)ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ruby concat3.rb
Rehearsal -----------------------------------------------
plus          0.000000   0.000000   0.000000 (  0.000076)
concat        0.000000   0.000000   0.000000 (  0.000070)
splash        0.000000   0.000000   0.000000 (  0.000099)
concat_all    0.000000   0.000000   0.000000 (  0.000136)
flat_map      0.000000   0.000000   0.000000 (  0.000138)
-------------------------------------- total: 0.000000sec

                  user     system      total        real
plus          0.000000   0.000000   0.000000 (  0.000051)
concat        0.000000   0.000000   0.000000 (  0.000059)
splash        0.000000   0.000000   0.000000 (  0.000083)
concat_all    0.000000   0.000000   0.000000 (  0.000120)
flat_map      0.000000   0.000000   0.000000 (  0.000173)
Rehearsal -----------------------------------------------
plus         43.040000   3.320000  46.360000 ( 46.351004)
concat       15.080000   3.870000  18.950000 ( 19.228059)
splash       49.680000   4.820000  54.500000 ( 54.587707)
concat_all   51.840000   5.260000  57.100000 ( 57.114867)
flat_map     17.380000   5.340000  22.720000 ( 22.716987)
------------------------------------ total: 199.630000sec

                  user     system      total        real
plus         42.880000   3.600000  46.480000 ( 46.506013)
concat       17.230000   5.290000  22.520000 ( 22.890809)
splash       60.300000   7.480000  67.780000 ( 67.878534)
concat_all   54.910000   6.480000  61.390000 ( 61.404383)
flat_map     17.310000   5.570000  22.880000 ( 23.223789)0 0.040000 16.100000 ( 11.737483)
 concat 15.950000 0.030000 15.980000 ( 10.480468)
 splash 47.870000 0.130000 48.000000 ( 22.668069)
 concat_all 19.150000 0.030000 19.180000 ( 13.934314)
 flat_map 16.850000 0.020000 16.870000 ( 10.862716)
cat concat3.rb
require 'benchmark'
N = (ENV['TIMES'] || 100).to_i

class Array
  def concat_all
    self.reduce([],:+)
  end
end

# small arrays
a = (1..10).to_a
b = (11..20).to_a
c = (21..30).to_a

Benchmark.bmbm do |r|
  r.report('plus       ')  { N.times { a + b + c }}
  r.report('concat     ') { N.times { [].concat(a).concat(b).concat(c) }}
  r.report('splash     ') { N.times {[*a,c].flat_map(&:itself)} }
end

#large arrays
a = (1..10_000_000).to_a
b = (10_000_001..20_000_000).to_a
c = (20_000_001..30_000_000).to_a

Benchmark.bmbm do |r|
  r.report('plus       ')  { N.times { a + b + c }}
  r.report('concat     ') { N.times { [].concat(a).concat(b).concat(c) }}
  r.report('splash     ') { N.times {[*a,c].flat_map(&:itself)} }
end

MRI Ruby和jRuby之间的性能差异

解决方法