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From "Sandy Ryza (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (MAPREDUCE-4922) Request with multiple data local nodes can cause NPE in AppSchedulingInfo
Date Fri, 08 Feb 2013 22:45:13 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4922?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sandy Ryza resolved MAPREDUCE-4922.
-----------------------------------

    Resolution: Won't Fix

This is the expected behavior
                
> Request with multiple data local nodes can cause NPE in AppSchedulingInfo
> -------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-4922
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4922
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: applicationmaster, mr-am, mrv2, scheduler
>    Affects Versions: 2.0.2-alpha
>            Reporter: Sandy Ryza
>            Assignee: Sandy Ryza
>
> With the way that the schedulers work, each request for a container on a node must consist
of 3 ResourceRequests - one on the node, one on the rack, and one with *.
> AppSchedulingInfo tracks the outstanding requests.  When a node is assigned a node-local
container, allocateNodeLocal decrements the outstanding requests at each level - node, rack,
and *.  If the rack requests reach 0, it removes the mapping.
> A mapreduce task with multiple data local nodes submits multiple container requests,
one for each node.  It also submits one for each unique rack, and one for *.  If there are
fewer unique racks than data local nodes, this means that fewer rack-local ResourceRequests
will be submitted than node-local ResourceRequests, so the rack-local mapping will be deleted
before all the node-local requests are allocated and an NPE will come up the next time a node-local
request from that rack is allocated.

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