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https://issues.apache.org/jira/browse/HADOOP-9124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568916#comment-13568916
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Surenkumar Nihalani commented on HADOOP-9124:
---------------------------------------------
There is a very small issue:
My latest attachment had this:
{code}
+ // entrySets are now same
+ failureReason = "Two SortedMapWritables with same entry sets formed in
different order have different hashcode";
+ assertEquals(failureReason, mapA.hashCode(), mapB.hashCode());
+ failureReason = "Two SortedMapWritables with same entry sets formed in
different order are no longer equal";
+ assertEquals(failureReason, mapA, mapB);
+ assertEquals(failureReason, mapB, mapA);
{code}
while Karthik and Tom, your latest attachments have this,
{code}
+ // entrySets are now same
+ failureReason = "Two SortedMapWritables with same entry sets formed in
different order are now different";
+ assertEquals(failureReason, mapA.hashCode(), mapB.hashCode());
+ assertTrue(failureReason, mapA.equals(mapB));
+ assertTrue(failureReason, mapB.equals(mapA));
{code}
I don't know how branches end up merging, but, since [~kkambatl] mentioned it
during code review, so, I thought it was worth to point out.
> 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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