Mailing-List: contact java-dev-help@lucene.apache.org; run by ezmlm
Precedence: bulk
Reply-To: java-dev@lucene.apache.org
Message-ID: <11046956.1195837363272.JavaMail.jira@brutus>
Date: Fri, 23 Nov 2007 09:02:43 -0800 (PST)
From: "Yonik Seeley (JIRA)" <jira@apache.org>
To: java-dev@lucene.apache.org
Subject: [jira] Commented: (LUCENE-693) ConjunctionScorer - more tuneup
In-Reply-To: <7545754.1161643096551.JavaMail.root@brutus>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/LUCENE-693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12545082 ] 

Yonik Seeley commented on LUCENE-693:
-------------------------------------

Cool, I guess the differences are probably  due to a different processor type (I was using a P4).


> ConjunctionScorer - more tuneup
> -------------------------------
>
>                 Key: LUCENE-693
>                 URL: https://issues.apache.org/jira/browse/LUCENE-693
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Search
>    Affects Versions: 2.1
>         Environment: Windows Server 2003 x64, Java 1.6, pretty large index
>            Reporter: Peter Keegan
>         Attachments: conjunction.patch, conjunction.patch, conjunction.patch, conjunction.patch, conjunction.patch.nosort1
>
>
> (See also: #LUCENE-443)
> I did some profile testing with the new ConjuctionScorer in 2.1 and discovered a new bottleneck in ConjunctionScorer.sortScorers. The java.utils.Arrays.sort method is cloning the Scorers array on every sort, which is quite expensive on large indexes because of the size of the 'norms' array within, and isn't necessary. 
> Here is one possible solution:
>   private void sortScorers() {
> // squeeze the array down for the sort
> //    if (length != scorers.length) {
> //      Scorer[] temps = new Scorer[length];
> //      System.arraycopy(scorers, 0, temps, 0, length);
> //      scorers = temps;
> //    }
>     insertionSort( scorers,length );
>     // note that this comparator is not consistent with equals!
> //    Arrays.sort(scorers, new Comparator() {         // sort the array
> //        public int compare(Object o1, Object o2) {
> //          return ((Scorer)o1).doc() - ((Scorer)o2).doc();
> //        }
> //      });
>   
>     first = 0;
>     last = length - 1;
>   }
>   private void insertionSort( Scorer[] scores, int len)
>   {
>       for (int i=0; i<len; i++) {
>           for (int j=i; j>0 && scores[j-1].doc() > scores[j].doc();j-- ) {
>               swap (scores, j, j-1);
>           }
>       }
>       return;
>   }
>   private void swap(Object[] x, int a, int b) {
>     Object t = x[a];
>     x[a] = x[b];
>     x[b] = t;
>   }
>  
> The squeezing of the array is no longer needed. 
> We also initialized the Scorers array to 8 (instead of 2) to avoid having to grow the array for common queries, although this probably has less performance impact.
> This change added about 3% to query throughput in my testing.
> Peter

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org