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From "Yonik Seeley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-2504) sorting performance regression
Date Sat, 11 Sep 2010 16:29:33 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12908336#action_12908336
] 

Yonik Seeley commented on LUCENE-2504:
--------------------------------------

bq. This is all quite silly: we are only doing this to "game" hotspot into properly inlining/compiling
what is in fact an array lookup, just currently hidden behind method calls in the packed ints
impls. We really "shouldn't have to" do this custom source code specialization.

Yeah, but this is the way hotspot currently works, and I don't know if there are any plans
to change it.
Hotspot can be pretty aggressive at inlining, but then it deoptimizes when it turns out that
the inline is no longer valid (because of a different implementation).

It's something worth keeping in mind for the rest of Lucene too - bothin benchmarking and
design. Multiple implementations used from a single spot will not be inlined (if multiple
implementations are actually used in the same run).


> sorting performance regression
> ------------------------------
>
>                 Key: LUCENE-2504
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2504
>             Project: Lucene - Java
>          Issue Type: Bug
>    Affects Versions: 4.0
>            Reporter: Yonik Seeley
>             Fix For: 4.0
>
>         Attachments: LUCENE-2504.patch, LUCENE-2504.zip
>
>
> sorting can be much slower on trunk than branch_3x

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