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https://issues.apache.org/jira/browse/MAPREDUCE-5124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13663908#comment-13663908
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Tsuyoshi OZAWA commented on MAPREDUCE-5124:
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I apologize for delaying reply.
> So I would throw a ToBusyRetryLater type of exception for once time RPC calls
> when the AsyncDispatcher's queue is over a high water mark, but for
> heartbeats I would want them to scale the frequency based off of how busy the
> AsyncDispatcher is.
It's better idea. I'll try to implement both heartbeat-style RPC and one-time
RPC.
> AM lacks flow control for task events
> -------------------------------------
>
> Key: MAPREDUCE-5124
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5124
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mr-am
> Affects Versions: 2.0.3-alpha, 0.23.5
> Reporter: Jason Lowe
> Attachments: MAPREDUCE-5124-prototype.txt
>
>
> The AM does not have any flow control to limit the incoming rate of events
> from tasks. If the AM is unable to keep pace with the rate of incoming
> events for a sufficient period of time then it will eventually exhaust the
> heap and crash. MAPREDUCE-5043 addressed a major bottleneck for event
> processing, but the AM could still get behind if it's starved for CPU and/or
> handling a very large job with tens of thousands of active tasks.
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