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https://issues.apache.org/jira/browse/MAPREDUCE-5124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16236485#comment-16236485
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Jason Lowe commented on MAPREDUCE-5124:
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bq. So either we completely drop this approach or implement HADOOP-11552 for
Writable RPC calls as well.
...or change TaskUmbilicalProtocol to use protobufs which would be a lot more
sensible if we want to pursue the deferred call approach. See MAPREDUCE-6706.
WritableRpcEngine is something the community has tried get rid of already, so I
wouldn't recommend investing more engineering effort into it.
At this point I think the status coalesce approach I described above is
probably the simplest and least risky to implement.
> 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
> Assignee: Peter Bacsko
> Priority: Major
> Attachments: MAPREDUCE-5124-proto.2.txt, 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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