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https://issues.apache.org/jira/browse/HADOOP-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12619803#action_12619803
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Enis Soztutar commented on HADOOP-3702:
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# obviously, casting the DataOutputStream to OutputStream would resolve the
ambiguity. All these kind of references could be changed (if any) to first cast
the reference.
{code}
DataOutputStream dos = ...
...
conf.write((OutputStream)dos);
...
{code}
# Although the Chain classes are not exposed, it is always good practice to use
the generics. We can get rid of @SuppressWarnings({"unchecked"}) annotations.
# If you are confident that this does not introduce extra overhead, I'm fine
with this.
> 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
> Attachments: patch3702.txt, patch3702.txt, patch3702.txt,
> patch3702.txt, 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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