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Posted to issues@lucene.apache.org by "Michael McCandless (Jira)" <ji...@apache.org> on 2021/08/24 13:34:00 UTC

[jira] [Commented] (LUCENE-9972) Performance regression in NRTCachingDirectory

    [ https://issues.apache.org/jira/browse/LUCENE-9972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17403804#comment-17403804 ] 

Michael McCandless commented on LUCENE-9972:
--------------------------------------------

Hmm this issue remains open, and the workaround is rather dangerous as it could consume unbounded amounts of heap.  Does anyone have ideas how to fix this better?

> Performance regression in NRTCachingDirectory
> ---------------------------------------------
>
>                 Key: LUCENE-9972
>                 URL: https://issues.apache.org/jira/browse/LUCENE-9972
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/store
>    Affects Versions: 8.8.2
>            Reporter: Markus Gietzen
>            Priority: Major
>              Labels: performance
>
> This issue has been discussed here:
> [http://mail-archives.apache.org/mod_mbox/lucene-java-user/202105.mbox/%3cAM0PR02MB4963712F269C5BF70951F0A3EF2B9@AM0PR02MB4963.eurprd02.prod.outlook.com%3e]
>  
> Summary: To get the same speed as in 8.3 I have to overwrite NRTCachingDirectory#doCacheWrite
> in 8.8 with the implementation from 8.3. Otherwise it's magnitudes slower.
>  
> It seems that the solution for https://issues.apache.org/jira/browse/LUCENE-9115 increases the number of calls to native-OpenFile (due to falling down to MMAP-Directory) by a very  large amount.
> I understand the reasoning behind LUCENE-9115 but in fact it destroys the performance of our product. For now sub-classing NRTCachingDirectory with the old implementation of doCacheWrite() solves the issue but it would be great to have an "offical" solution of course.
>  



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