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From "Michael McCandless (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-3515) Possible slowdown of indexing/merging on 3.x vs trunk
Date Thu, 13 Oct 2011 16:31:12 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-3515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13126704#comment-13126704
] 

Michael McCandless commented on LUCENE-3515:
--------------------------------------------

I actually see 3.x running slower:

Trunk:
{noformat}
  Time taken indexing: 184
  Time taken closing: 2
  Time taken whole process: 187
{noformat}

3.x:
{noformat}
Time taken indexing: 205
  Time taken closing: 40
  Time taken whole process: 245
{noformat}

But, this is because 3.x does a level 2 merge just before close, and
the close must wait for that merge to complete.  Whereas trunk never
gets to the level 2 merge (only level 0/1), likely because trunk's RAM
efficiency is a better and so it packs more docs into each level 0 segment.

If we pushed the number of doc up to maybe 1.1M then we should
similarly see trunk trigger a level 2 merge.

Really when benchmarking indexing it's best to just close the IW
without waiting for merges; otherwise you're comparing apples &
oranges.

                
> Possible slowdown of indexing/merging on 3.x vs trunk
> -----------------------------------------------------
>
>                 Key: LUCENE-3515
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3515
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: core/index
>            Reporter: Michael McCandless
>             Fix For: 3.5, 4.0
>
>         Attachments: LUCENE-index-34.patch, LUCENE-index-40.patch, TestGenerationTime.java.3x,
TestGenerationTime.java.40
>
>
> Opening an issue to pursue the possible slowdown Marc Sturlese uncovered.

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