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https://issues.apache.org/jira/browse/YARN-3367?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15130065#comment-15130065
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Varun Saxena commented on YARN-3367:
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A couple of comments.
# When we are stopping the dispatcher, we are saying in log that we are
draining it but we are not really doing so.
I think we can try to drain the queue on stop and process the async events or
some sync event sitting in the queue. We would need to do this before we call
shutdownNow as that will interrupt the thread.
# nit : In TestTimelineClientV2Impl#testSyncCall, we have made an extra call to
{{client.setSleepBeforeReturn(true);}} which is not required.
> Replace starting a separate thread for post entity with event loop in
> TimelineClient
> ------------------------------------------------------------------------------------
>
> Key: YARN-3367
> URL: https://issues.apache.org/jira/browse/YARN-3367
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: timelineserver
> Affects Versions: YARN-2928
> Reporter: Junping Du
> Assignee: Naganarasimha G R
> Labels: yarn-2928-1st-milestone
> Attachments: YARN-3367-YARN-2928.v1.005.patch,
> YARN-3367-YARN-2928.v1.006.patch, YARN-3367-YARN-2928.v1.007.patch,
> YARN-3367-YARN-2928.v1.008.patch, YARN-3367-YARN-2928.v1.009.patch,
> YARN-3367-feature-YARN-2928.003.patch,
> YARN-3367-feature-YARN-2928.v1.002.patch,
> YARN-3367-feature-YARN-2928.v1.004.patch, YARN-3367.YARN-2928.001.patch,
> sjlee-suggestion.patch
>
>
> Since YARN-3039, we add loop in TimelineClient to wait for
> collectorServiceAddress ready before posting any entity. In consumer of
> TimelineClient (like AM), we are starting a new thread for each call to get
> rid of potential deadlock in main thread. This way has at least 3 major
> defects:
> 1. The consumer need some additional code to wrap a thread before calling
> putEntities() in TimelineClient.
> 2. It cost many thread resources which is unnecessary.
> 3. The sequence of events could be out of order because each posting
> operation thread get out of waiting loop randomly.
> We should have something like event loop in TimelineClient side,
> putEntities() only put related entities into a queue of entities and a
> separated thread handle to deliver entities in queue to collector via REST
> call.
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