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Date: Fri, 30 Mar 2012 09:22:36 +0000 (UTC)
From: "Dawid Weiss (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (LUCENE-3935) Optimize Kuromoji inner loop -
 rewrite ConnectionCosts.get() method
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    [ https://issues.apache.org/jira/browse/LUCENE-3935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13242183#comment-13242183 ] 

Dawid Weiss commented on LUCENE-3935:
-------------------------------------

bq. I did this hastily last night and results suggested that there wasn't a lot to be gained on Mac OS X

I agree it may not be noticeable because there are so many factors kicking in here (smaller structure - better cpu cache utilization vs. larger structure - potentially faster access to each value but potential cache misses). 

Makes sense to keep short[] in place, ignore my comment.
                
> Optimize Kuromoji inner loop - rewrite ConnectionCosts.get() method
> -------------------------------------------------------------------
>
>                 Key: LUCENE-3935
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3935
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: modules/analysis
>    Affects Versions: 3.6, 4.0
>            Reporter: Christian Moen
>            Assignee: Christian Moen
>         Attachments: LUCENE-3935.patch
>
>
> I've been profiling Kuromoji, and not very surprisingly, method {{ConnectionCosts.get(int forwardId, int backwardId)}} that looks up costs in the Viterbi is called many many times and contributes to more processing time than I had expected.
> This method is currently backed by a {{short[][]}}.  This data stored here structure is a two dimensional array with both dimensions being fixed with 1316 elements in each dimension.  (The data is {{matrix.def}} in MeCab-IPADIC.)
> We can rewrite this to use a single one-dimensional array instead, and we will at least save one bounds check, a pointer reference, and we should also get much better cache utilization since this structure is likely to be in very local CPU cache.
> I think this will be a nice optimization.  Working on it... 

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