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Posted to common-dev@hadoop.apache.org by "Chris Douglas (JIRA)" <ji...@apache.org> on 2008/06/25 06:30:45 UTC

[jira] Updated: (HADOOP-3630) CompositeRecordReader: key and values can be in uninitialized state if files being joined have no records

     [ https://issues.apache.org/jira/browse/HADOOP-3630?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chris Douglas updated HADOOP-3630:
----------------------------------

    Attachment: 3630-0.patch

bq. I think this occurs because CompositeRecordReader#add() [Hadoop 0.17.0, line 138] doesn't call rr.hasNext() to check if the RecordReader has any records before it adds it to the PriorityQueue. Is this a bug or expected behaviour?

This is definitely a bug, and your diagnosis is exactly right.

Attaching a fix and a testcase.

> CompositeRecordReader: key and values can be in uninitialized state if files being joined have no records
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3630
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3630
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.17.0
>            Reporter: Jingkei Ly
>             Fix For: 0.19.0
>
>         Attachments: 3630-0.patch
>
>
> I am using org.apache.hadoop.mapred.join.CompositeInputFormat to do an outer-join across a number of SequenceFiles. This works fine in most circumstances, but I get NullPointerExceptions/uninitialized data (where Writable#readFields() has not been called) when some of the files being joined have no records in them.

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