[
https://issues.apache.org/jira/browse/MAPREDUCE-4892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13589527#comment-13589527
]
Hudson commented on MAPREDUCE-4892:
-----------------------------------
Integrated in Hadoop-Mapreduce-trunk #1358 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk/1358/])
MAPREDUCE-4892. Modify CombineFileInputFormat to not skew input slits'
allocation on small clusters. Contributed by Bikas Saha. (Revision 1450912)
Result = FAILURE
vinodkv :
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1450912
Files :
* /hadoop/common/trunk/hadoop-mapreduce-project/CHANGES.txt
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/input/CombineFileInputFormat.java
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/mapreduce/lib/input/TestCombineFileInputFormat.java
> CombineFileInputFormat node input split can be skewed on small clusters
> -----------------------------------------------------------------------
>
> Key: MAPREDUCE-4892
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4892
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Bikas Saha
> Assignee: Bikas Saha
> Fix For: 2.0.4-beta
>
> Attachments: MAPREDUCE-4892.1.alt.patch, MAPREDUCE-4892.1.alt.patch,
> MAPREDUCE-4892.1.patch
>
>
> The CombineFileInputFormat split generation logic tries to group blocks by
> node in order to create splits. It iterates through the nodes and creates
> splits on them until there aren't enough blocks left on a node that can be
> grouped into a valid split. If the first few nodes have a lot of blocks on
> them then they can end up getting a disproportionately large share of the
> total number of splits created. This can result in poor locality of maps.
> This problem is likely to happen on small clusters where its easier to create
> a skew in the distribution of blocks on nodes.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
