Java List to Ruby Array conversion ~100% slower than primitive array conversion
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Key: JRUBY-3910
URL: http://jira.codehaus.org/browse/JRUBY-3910
Project: JRuby
Issue Type: Improvement
Components: Performance
Affects Versions: JRuby 1.3.1, JRuby 1.4
Environment: MacOSX 10.5.8
java version "1.6.0_13"
Java(TM) SE Runtime Environment (build 1.6.0_13-b03-211)
Java HotSpot(TM) 64-Bit Server VM (build 11.3-b02-83, mixed mode)
Reporter: Michael Rykov
Fix For: JRuby 1.4, JRuby 1.3.1
Attachments: bench.rb
On both jRuby 1.3.1 and jRuby 1.4 (edge), I found that converting Java Lists to
Ruby Array actually performs worse than converting the Java List to a Java
Array to a Ruby Array. Performance of the 2-step conversion is up to 50%
faster.
Here are the results
{code}
$ jruby -v
jruby 1.4.0dev (ruby 1.8.7p174) (2009-08-23 6f772bf) (Java HotSpot(TM) 64-Bit
Server VM 1.6.0_13) [x86_64-java]
$ jruby --server ./bench.rb
Rehearsal -----------------------------------------------------
list.to_a 2.996000 0.000000 2.996000 ( 2.841000)
list.toArray.to_a 1.821000 0.000000 1.821000 ( 1.821000)
array.to_a 0.772000 0.000000 0.772000 ( 0.772000)
-------------------------------------------- total: 5.589000sec
user system total real
list.to_a 1.875000 0.000000 1.875000 ( 1.875000)
list.toArray.to_a 0.916000 0.000000 0.916000 ( 0.916000)
array.to_a 0.760000 0.000000 0.760000 ( 0.760000)
{code}
Knowing this was really helpful in getting my Google App Engine application to
stop hitting the request time limit when loading arrays from the Datastore
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