[jruby-dev] [jira] (JRUBY-6841) State file use in UUID gem causes severe performance degradation

Tue, 14 Aug 2012 07:11:54 -0700

Issue Type: Bug Bug
Affects Versions: JRuby 1.7.0.pre2
Assignee: Unassigned
Components: Core Classes/Modules, Performance
Created: 14/Aug/12 9:11 AM
Description:

The 'uuid' gem uses a state file to maintain some global sequencing. However when using this file under JRuby, performance is severely impacted. It seems like the problem is its repeated reopening of the file for every UUID generated.

Benchmark:

require 'benchmark'
require 'uuid'

(ARGV[0] || 5).to_i.times do
  Benchmark.bm(20) do |bm|
    bm.report("default") do
      uuid = UUID.new
      100_000.times { uuid.generate }
    end
    bm.report("default, no state file") do
      old_state_file = UUID.state_file
      UUID.state_file = false
      uuid = UUID.new
      100_000.times { uuid.generate }
      UUID.state_file = old_state_file
    end
  end
end



Numbers:





system ~/projects/jruby/tmp/uuid $ jruby -Ilib bench_uuid.rb 
                           user     system      total        real
default               10.610000   3.870000  14.480000 (  9.157000)
default, no state file  1.390000   0.370000   1.760000 (  0.767000)
                           user     system      total        real
default                4.420000   3.660000   8.080000 (  6.886000)
default, no state file  0.370000   0.000000   0.370000 (  0.352000)
                           user     system      total        real
default                3.990000   3.610000   7.600000 (  6.723000)
default, no state file  0.400000   0.000000   0.400000 (  0.349000)
                           user     system      total        real
default                3.540000   3.550000   7.090000 (  6.580000)
default, no state file  0.380000   0.000000   0.380000 (  0.339000)
                           user     system      total        real
default                3.520000   3.510000   7.030000 (  6.551000)
default, no state file  0.350000   0.000000   0.350000 (  0.328000)

system ~/projects/jruby/tmp/uuid $ rvm 1.9.3 do ruby -Ilib bench_uuid.rb 
                           user     system      total        real
default                0.740000   0.010000   0.750000 (  0.736922)
default, no state file  0.730000   0.000000   0.740000 (  0.759890)
                           user     system      total        real
default                0.730000   0.000000   0.730000 (  0.734763)
default, no state file  0.730000   0.010000   0.740000 (  0.727520)
                           user     system      total        real
default                0.730000   0.000000   0.730000 (  0.734713)
default, no state file  0.760000   0.000000   0.760000 (  0.755858)
                           user     system      total        real
default                0.750000   0.000000   0.750000 (  0.759376)
default, no state file  0.730000   0.000000   0.730000 (  0.730918)
                           user     system      total        real
default                0.730000   0.010000   0.740000 (  0.730651)
default, no state file  0.730000   0.000000   0.730000 (  0.726645)
Fix Versions: JRuby 1.7.0.RC1
Project: JRuby
Priority: Major Major
Reporter: Charles Oliver Nutter
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