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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5381) ExtendedBlock#hashCode should use both blockId and block pool ID
Date Sun, 11 May 2014 01:58:17 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13994384#comment-13994384
] 

Hudson commented on HDFS-5381:
------------------------------

SUCCESS: Integrated in Hadoop-Hdfs-trunk #1752 (See [https://builds.apache.org/job/Hadoop-Hdfs-trunk/1752/])
HDFS-5381. ExtendedBlock#hashCode should use both blockId and block pool ID (Benoy Antony
via Colin Patrick McCabe) (cmccabe: http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1593346)
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ExtendedBlock.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/TestExtendedBlock.java


> ExtendedBlock#hashCode should use both blockId and block pool ID
> ----------------------------------------------------------------
>
>                 Key: HDFS-5381
>                 URL: https://issues.apache.org/jira/browse/HDFS-5381
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: federation
>    Affects Versions: 2.3.0
>            Reporter: Colin Patrick McCabe
>            Assignee: Benoy Antony
>            Priority: Minor
>             Fix For: 2.5.0
>
>         Attachments: HDFS-5381.001.patch, HDFS-5381.002.patch
>
>
> {{ExtendedBlock#hashCode}} contains both a block pool ID and a block ID.  The {{equals}}
function checks both.  However, {{hashCode}} only uses block ID.  Since HDFS-4645, block IDs
are now allocated sequentially.  This means that there will be a lot of hash collisions when
federation is in use.  We should use both block ID and block pool ID in {{hashCode}} to prevent
this.



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