Forum: IronRuby Performance issues with json_pure under IronRuby

Hi,
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):
http://gist.github.com/498997

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
http://clorophilla.net/
http://twitter.com/JoL1hAHN

I've narrowed the problem down. It's somewhere in the 
StringScanner.Match
method (probably inside RubyRegex.Match).

The next IR code (I've put in on pastebin) results with the same 
performance
problem where MRI is about 100 (!) times faster than IronRuby:
http://pastebin.com/cc9FvUfz.

Shay.

Great work. Could you file a bug so that we track this perf issue?

Tomas

From: ironruby-core-bounces@rubyforge.org 
[mailto:ironruby-core-bounces@rubyforge.org] On Behalf Of Shay Friedman
Sent: Friday, July 30, 2010 12:37 PM
To: ironruby-core@rubyforge.org
Subject: Re: [Ironruby-core] Performance issues with json_pure under 
IronRuby

I've narrowed the problem down. It's somewhere in the 
StringScanner.Match method (probably inside RubyRegex.Match).

The next IR code (I've put in on pastebin) results with the same 
performance problem where MRI is about 100 (!) times faster than 
IronRuby: http://pastebin.com/cc9FvUfz.

Shay.

On Fri, Jul 30, 2010 at 2:03 PM, Daniele Alessandri 
<suppakilla@gmail.com<mailto:suppakilla@gmail.com>> wrote:
Hi,
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):
http://gist.github.com/498997

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
http://clorophilla.net/
http://twitter.com/JoL1hAHN

Done - http://ironruby.codeplex.com/workitem/4966

Shay.

On Fri, Jul 30, 2010 at 11:17 PM, Tomas Matousek <

Just added a comment on the bugtracker for this issue, it seems like
the /n modifier in the regexp is the cause of the abnormal slow down.

On Fri, Jul 30, 2010 at 22:41, Shay Friedman <shay.friedman@gmail.com> 
wrote:
>>
>>
>>
>> yesterday I was testing the json library under IronRuby and,
>>       user     system      total        real
>>
>>
> http://rubyforge.org/mailman/listinfo/ironruby-core
>
>



--
Daniele Alessandri
http://clorophilla.net/
http://twitter.com/JoL1hAHN