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https://issues.apache.org/jira/browse/MAPREDUCE-5124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Peter Bacsko updated MAPREDUCE-5124:
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Attachment: MAPREDUCE-5124-001.patch
Thanks for the comments [~jlowe]. I uploaded the first patch.
What's new:
1. Your comments have been addressed
2. I added new tests and refactored {{TestTaskAttemptListenerImpl}} heavily
because there was a lot of copy-paste there. I think it's much nicer now.
I still have one question regarding counters. When I was writing the tests, it
turned out that {{Counters}} object inside the {{TaskStatus}} cannot be null.
If it is, then we got an NPE thrown from the constructor of
{{AbstractCounters}}. I'm talking about this part:
{noformat}
taskAttemptStatus.counters = new org.apache.hadoop.mapreduce.Counters(
taskStatus.getCounters());
{noformat}
We already know that counters are always sent from MR tasks, but what about
Tez? I checked the Tez codebase, but I haven't found any call to
{{statusUpdate()}}.
> 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-5124-001.patch,
> MAPREDUCE-5124-CoalescingPOC-1.patch, MAPREDUCE-5124-CoalescingPOC2.patch,
> MAPREDUCE-5124-CoalescingPOC3.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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