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From "Hudson (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7761) Improve performance of raw comparisons
Date Thu, 27 Oct 2011 13:02:36 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13137070#comment-13137070
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Hudson commented on HADOOP-7761:
--------------------------------

Integrated in Hadoop-Mapreduce-trunk #873 (See [https://builds.apache.org/job/Hadoop-Mapreduce-trunk/873/])
    HADOOP-7761. Improve the performance of raw comparisons. Contributed by Todd Lipcon.

todd : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1189613
Files : 
* /hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt
* /hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/FastByteComparisons.java
* /hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableComparator.java

                
> 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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