hadoop-common-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Surenkumar Nihalani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-9124) SortedMapWritable violates contract of Map interface for equals() and hashCode()
Date Fri, 01 Feb 2013 18:06:14 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-9124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568916#comment-13568916
] 

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.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message