[Ironruby-core] Performance issues with json_pure under IronRuby

Daniele Alessandri suppakilla at gmail.com
Fri Jul 30 07:03:50 EDT 2010

yesterday I was testing the json library under IronRuby and,
comparisons with other implementations aside, I noticed that the
"pure" variant performs so bad under IronRuby that it just doesn't
feel normal at all. This is the result for my test with a ~500KB JSON
file parsed under IronRuby 1.1.0 (.NET 4):

C:\IronRuby\v1.1.0>ir json_speed.rb pure
Rehearsal ------------------------------------
 474.906250  39.421875 514.328125 (394.262696)
------------------------- total: 514.328125sec

       user     system      total        real
 482.531250  43.140625 525.671875 (384.509766)

Here is the full gist with also the results for the same test run
using other implementations (JRuby 1.5 and the latest MRI 1.8.6):

I haven't figured yet where the bottleneck is, and the fact that it's
slower on the second run makes things even weirder since the cold
execution overhead shouldn't be there anymore. Any idea about why is
it so slow?

Daniele Alessandri

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