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https://issues.apache.org/jira/browse/MAPREDUCE-4893?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13575156#comment-13575156
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Hudson commented on MAPREDUCE-4893:
-----------------------------------
Integrated in Hadoop-Hdfs-0.23-Build #520 (See
[https://builds.apache.org/job/Hadoop-Hdfs-0.23-Build/520/])
MAPREDUCE-4893. MR AppMaster can do sub-optimal assignment of containers
to map tasks leading to poor node locality. Contributed by Bikas Saha (Revision
1444276)
Result = SUCCESS
jlowe : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1444276
Files :
* /hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/CHANGES.txt
*
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java
*
/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/TestRMContainerAllocator.java
> MR AppMaster can do sub-optimal assignment of containers to map tasks leading
> to poor node locality
> ---------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-4893
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4893
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: applicationmaster
> Reporter: Bikas Saha
> Assignee: Bikas Saha
> Fix For: 2.0.3-alpha, 0.23.7
>
> Attachments: MAPREDUCE-4893.1.patch, MAPREDUCE-4893.2.patch,
> MAPREDUCE-4893.3.patch
>
>
> Say the MR AppMaster asks the RM for 3 containers on nodes n1, n2 and n3.
> There are 10 node n1-n10 in the same rack. The RM can give it allocated
> containers in the list order n5, n2, n1. The way AM map->container assignment
> happens, the AM will try to assign node local maps to n5, failing which it
> will assign rack local maps to n5. These rack local maps could be node local
> on n2 and n1 and would have been assigned to containers on n1 and n2 if the
> AM had not made an early rack local match for them on n5. This can lead to
> poor locality.
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