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https://issues.apache.org/jira/browse/MAPREDUCE-3899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13259968#comment-13259968
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Siddharth Seth commented on MAPREDUCE-3899:
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Bikas, I'm not sure that the locking isn't needed. It's broken the way it is
rightnow though.
ApplicationMasterService seems to be written to handle one bad request (caused
by network issues etc). allocate() does more than a scheduler.allocate - node
state changes, newly allocated containers etc. All of that needs to be part of
a single response. Without the lock - that may not happen. Locking on the
AppAttemptId or the AppId itself is probably a better option, and also needs to
cover the retrieval of the last response.
Also, we shouldn't be logging in the allocate call (not at INFO level anyway).
That'll flood the RM logs.
> Locking not correct in
> org.apache.hadoop.yarn.server.resourcemanager.ApplicationMasterService.allocate(AllocateRequest
> request)
> -------------------------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-3899
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3899
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2, resourcemanager
> Affects Versions: 0.23.0
> Reporter: Bikas Saha
> Assignee: Bikas Saha
> Fix For: 0.23.0
>
> Attachments: MAPREDUCE-3899-branch-0.23.patch
>
>
> Looks like the lock taken in this is broken. It takes a lock on lastResponse
> object and then puts a new lastResponse object into the map. At this point a
> new thread entering this function will get a new lastResponse object and will
> be able to take its lock and enter the critical section. Presumably we want
> to limit one response per app attempt. So the lock could be taken on the
> ApplicationAttemptId key of the response map object.
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