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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-6881) The efficient comparators aren't always used except for BytesWritable and Text
Date Mon, 26 Jul 2010 22:48:18 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-6881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12892521#action_12892521
] 

Hadoop QA commented on HADOOP-6881:
-----------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12450525/HADOOP-6881.patch
  against trunk revision 979387.

    +1 @author.  The patch does not contain any @author tags.

    +1 tests included.  The patch appears to include 3 new or modified tests.

    -1 javadoc.  The javadoc tool appears to have generated 1 warning messages.

    +1 javac.  The applied patch does not increase the total number of javac compiler warnings.

    +1 findbugs.  The patch does not introduce any new Findbugs warnings.

    +1 release audit.  The applied patch does not increase the total number of release audit
warnings.

    +1 core tests.  The patch passed core unit tests.

    +1 contrib tests.  The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-h4.grid.sp2.yahoo.net/636/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-h4.grid.sp2.yahoo.net/636/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-h4.grid.sp2.yahoo.net/636/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-h4.grid.sp2.yahoo.net/636/console

This message is automatically generated.

> The efficient comparators aren't always used except for BytesWritable and Text
> ------------------------------------------------------------------------------
>
>                 Key: HADOOP-6881
>                 URL: https://issues.apache.org/jira/browse/HADOOP-6881
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 0.20.0
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>             Fix For: 0.20.3
>
>         Attachments: h-6881.patch, HADOOP-6881.patch, HADOOP-6881.patch
>
>
> When we moved from Java 4 to Java 5 (and then 6), there was a change in the JVM semantics
such that references to a class such as IntWritable.class no longer forces initialization.
Since all of the Writables depend on their class static blocks to register their fast comparators,
that can happen *after* we look up the comparator. In that case, the framework will fall back
to the generic comparator that deserializes both keys and does the object compare, which may
cause a huge slow down in the sort.

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