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https://issues.apache.org/jira/browse/YARN-744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13709064#comment-13709064
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Omkar Vinit Joshi commented on YARN-744:
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bq. BTW, is it convenient to write a test case for concurrent allocation? Like
TestClientRMService#testConcurrentAppSubmit.
yeah wrote one...
bq. The passed in appAttemptId for an app currently seems to be the same
object, such that it can be used to for synchronized blocks, but I agree with
the idea of wrapper, because it is more predictable and stand-alone in
ApplicationMasterService.
locking on appAttemptId in case of allocate / RegisterApplicationMaster call
won't work. They are coming from client...can't guarantee that they are
identical in terms grabbing a lock.. thoughts?
> Race condition in ApplicationMasterService.allocate .. It might process same
> allocate request twice resulting in additional containers getting allocated.
> ---------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: YARN-744
> URL: https://issues.apache.org/jira/browse/YARN-744
> Project: Hadoop YARN
> Issue Type: Bug
> Components: resourcemanager
> Reporter: Bikas Saha
> Assignee: Omkar Vinit Joshi
> Attachments: MAPREDUCE-3899-branch-0.23.patch,
> YARN-744-20130711.1.patch, YARN-744.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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