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https://issues.apache.org/jira/browse/MAPREDUCE-5124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16247678#comment-16247678
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Peter Bacsko commented on MAPREDUCE-5124:
-----------------------------------------
Thanks Jason.
Are you sure we can't just replace the status updates? I checked the code of
TaskReporter, to it seems that counters/fetch failures cannot be removed, only
altered/increased. If you think about it, we send updates in every 3 seconds
anyway - so if it's a problem, then it would appear on the client side, too
(that is, losing data).
I agree with your comment regarding the mapping - passing a reference in the
event is a good idea.
> 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
> Attachments: MAPREDUCE-5124-CoalescingPOC-1.patch,
> MAPREDUCE-5124-CoalescingPOC2.patch, 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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