[jira] Commented: (MAPREDUCE-1820) InputSampler does not create a deep copy of the key object when creating a sample, which causes problems with some formats like SequenceFile

["Hudson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12977100#action_12977100 ] 

Hudson commented on MAPREDUCE-1820:
-----------------------------------

Integrated in HBase-TRUNK #1701 (See [https://hudson.apache.org/hudson/job/HBase-TRUNK/1701/])
    HBASE-3392. Update backport of InputSampler to reflect MAPREDUCE-1820


> InputSampler does not create a deep copy of the key object when creating a sample, which causes problems with some formats like SequenceFile<Text,Text>
> -------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1820
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1820
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Alex Kozlov
>            Assignee: Alex Kozlov
>             Fix For: 0.22.0
>
>         Attachments: M1820-4.patch, M1820-5.patch, MAPREDUCE-1820-2.patch, MAPREDUCE-1820-3.patch, MAPREDUCE-1820.patch
>
>   Original Estimate: 2h
>  Remaining Estimate: 2h
>
> I tried to use the InputSampler on a SequenceFile<Text,Text> and found that it comes up with duplicate keys in the sample.  The problem was tracked down to the fact that the Text object returned from the reader is essentially a wrapper pointing to a byte array, which changes as the sequence file reader progresses.  There was also a bug in that the reader should be initialized before the use.  The am attaching a patch that fixes both of the issues.  --Alex K

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