State file use in UUID gem causes severe performance degradation #2355
Description
From http://jira.codehaus.org/browse/JRUBY-6841
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 '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)