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Date: Thu, 27 Oct 2011 18:26:33 +0000 (UTC)
From: "Doug Cutting (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HADOOP-7761) Improve performance of raw
 comparisons
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    [ https://issues.apache.org/jira/browse/HADOOP-7761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13137361#comment-13137361 ] 

Doug Cutting commented on HADOOP-7761:
--------------------------------------

Do you think there's any point in trying to push the support for offsets upstream into Guava?
                
> Improve performance of raw comparisons
> --------------------------------------
>
>                 Key: HADOOP-7761
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7761
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: io, performance, util
>    Affects Versions: 0.23.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>             Fix For: 0.24.0
>
>         Attachments: hadoop-7761.txt, hadoop-7761.txt, hadoop-7761.txt, hadoop-7761.txt
>
>
> Guava has a nice implementation of lexicographical byte-array comparison that uses sun.misc.Unsafe to compare unsigned byte arrays long-at-a-time. Their benchmarks show it as being 2x more CPU-efficient than the equivalent pure-Java implementation. We can easily integrate this into WritableComparator.compareBytes to improve CPU performance in the shuffle.

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