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Date: Sat, 14 May 2016 17:10:12 +0000 (UTC)
From: "Harinder Singh Bedi (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Message-ID: <JIRA.12466177.1275653598000.190968.1463245812926@Atlassian.JIRA>
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References: <JIRA.12466177.1275653598000@Atlassian.JIRA> <JIRA.12466177.1275653598220@arcas>
Subject: [jira] [Commented] (MAPREDUCE-1842) JobID.forName() creates JobID
 instances that break equality
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archived-at: Sat, 14 May 2016 17:10:15 -0000


    [ https://issues.apache.org/jira/browse/MAPREDUCE-1842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15283618#comment-15283618 ] 

Harinder Singh Bedi commented on MAPREDUCE-1842:
------------------------------------------------

This issue has effect the BLUR project as well. https://issues.apache.org/jira/browse/BLUR-449. If the plan to fix this is by changing the equals method then the BLUR issue will also be resolved.

> JobID.forName() creates JobID instances that break equality
> -----------------------------------------------------------
>
>                 Key: MAPREDUCE-1842
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1842
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: job submission
>    Affects Versions: 0.20.2
>            Reporter: Age Mooij
>
> We have some code that uses serialization to store org.apache.hadoop.mapreduce.JobID instances (among other things). Since org.apache.hadoop.mapreduce.JobID is not serializable, we store the String representation and use org.apache.hadoop.mapreduce.JobID.forName(String) to read it back.
> Unfortunately the instance created by that method is not equal to the same id as created by the constructor. Here's a unit test for the problem:
> @Test
> public void forNameCopyShouldProduceInstanceEqualToOriginal() {
>     JobID jobId1 = new JobID("original", 1);
>     JobID jobId2 = JobID.forName(jobId1.toString());
>     assertEquals(jobId1, jobId2);
> }
> forName(String) produces a backwards compatible instance from the old mapred package but the equals method shared by them both uses this.getClass() == that.getClass() and that causes the incompatible instances.
> I know this backwards compatible stuff is important but could you please fix this ? The simplest fix would be to change the implementation of equals() or override it in the backwards compatibillity version of JobID in the old mapred package


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