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:\jruby\bin\jruby -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)
解决方法
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: 145.180000secuser 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)0 0.040000 16.100000 ( 11.737483)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)
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