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From "Karthik Kambatla (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-9124) SortedMapWritable violates contract of Map interface for equals() and hashCode()
Date Fri, 01 Feb 2013 17:54:12 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-9124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Karthik Kambatla updated HADOOP-9124:
-------------------------------------

     Target Version/s: 1.2.0
    Affects Version/s: 1.1.1
    
> SortedMapWritable violates contract of Map interface for equals() and hashCode()
> --------------------------------------------------------------------------------
>
>                 Key: HADOOP-9124
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9124
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: io
>    Affects Versions: 1.1.1, 2.0.2-alpha
>            Reporter: Patrick Hunt
>            Assignee: Surenkumar Nihalani
>            Priority: Minor
>             Fix For: 2.0.3-alpha
>
>         Attachments: hadoop-9124-branch1.patch, HADOOP-9124.patch, HADOOP-9124.patch,
HADOOP-9124.patch, HADOOP-9124.patch, HADOOP-9124.patch, HADOOP-9124.patch, HADOOP-9124.patch,
HADOOP-9124.patch, HADOOP-9124.patch, HADOOP-9124.patch
>
>
> This issue is similar to HADOOP-7153. It was found when using MRUnit - see MRUNIT-158,
specifically https://issues.apache.org/jira/browse/MRUNIT-158?focusedCommentId=13501985&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13501985
> --
> o.a.h.io.SortedMapWritable implements the java.util.Map interface, however it does not
define an implementation of the equals() or hashCode() methods; instead the default implementations
in java.lang.Object are used.
> This violates the contract of the Map interface which defines different behaviour for
equals() and hashCode() than Object does. More information here: http://download.oracle.com/javase/6/docs/api/java/util/Map.html#equals(java.lang.Object)
> The practical consequence is that SortedMapWritables containing equal entries cannot
be compared properly. We were bitten by this when trying to write an MRUnit test for a Mapper
that outputs MapWritables; the MRUnit driver cannot test the equality of the expected and
actual MapWritable objects.

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