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Date: Mon, 7 Aug 2006 02:39:15 -0700 (PDT)
From: "Johan Stuyts (JIRA)" <jira@apache.org>
To: java-dev@lucene.apache.org
Subject: [jira] Commented: (LUCENE-639) [PATCH] Slight performance
 improvement for readVInt() of IndexInput
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    [ http://issues.apache.org/jira/browse/LUCENE-639?page=comments#action_12426181 ] 
            
Johan Stuyts commented on LUCENE-639:
-------------------------------------

Yonik, I agree that instead of using artificial data sets instead of real ones might influence the results. Getting my hands on real, large data is going to be difficult.

I also think that you drew your conclusion too fast. You only ran the tests on a few JVMs. As you can see from the test results that I submitted, the differences between JVMs are significant.

There is no perfect algorithm which runs better on all JVMs, but I think that algorithms that run better on most JVMs exist.


> [PATCH] Slight performance improvement for readVInt() of IndexInput
> -------------------------------------------------------------------
>
>                 Key: LUCENE-639
>                 URL: http://issues.apache.org/jira/browse/LUCENE-639
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>    Affects Versions: 2.0.0
>            Reporter: Johan Stuyts
>            Priority: Minor
>         Attachments: Lucene2ReadVIntPerformance.patch, readVInt performance results.pdf, ReadVIntPerformanceMain.java
>
>
> By unrolling the loop in readVInt() I was able to get a slight, about 1.8 %, performance improvement for this method. The test program invoked the method over 17 million times on each run.
> I ran the performance tests on:
> - Windows XP Pro SP2
> - Sun JDK 1.5.0_07
> - YourKit 5.5.4
> - Lucene trunk

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