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https://issues.apache.org/jira/browse/HADOOP-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alejandro Abdelnur updated HADOOP-3702:
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Attachment: patch3702.txt
Integrating Owen's comments:
* Modified Configuration to be a Writable
* Modified WritableUtils to have methods to convert Writable to/from String
* Modified Chain to use above methods instead hack with Properties
* Using hadoop DataOutputBuffer
* Using if/else Sun's sytle
I could not figure out the comment on taskAttempId as the patch is not using
taskId at all to find out if its a map or reduce task. The ChainMapper and
ChainReducer create a Chain to delegate common logic and at creation time it
indicates what is to be use for.
> add support for chaining Maps in a single Map and after a Reduce [M*/RM*]
> -------------------------------------------------------------------------
>
> Key: HADOOP-3702
> URL: https://issues.apache.org/jira/browse/HADOOP-3702
> Project: Hadoop Core
> Issue Type: New Feature
> Components: mapred
> Environment: all
> Reporter: Alejandro Abdelnur
> Assignee: Alejandro Abdelnur
> Priority: Minor
> Attachments: patch3702.txt, patch3702.txt, patch3702.txt,
> patch3702.txt, patch3702.txt, patch3702.txt
>
>
> On the same input, we usually need to run multiple Maps one after the other
> without no Reduce. We also have to run multiple Maps after the Reduce.
> If all pre-Reduce Maps are chained together and run as a single Map a
> significant amount of Disk I/O will be avoided.
> Similarly all post-Reduce Maps can be chained together and run in the Reduce
> phase after the Reduce.
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