[
https://issues.apache.org/jira/browse/MAPREDUCE-5124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16154117#comment-16154117
]
Miklos Szegedi commented on MAPREDUCE-5124:
-------------------------------------------
[~jlowe], I absolutely agree that the heartbeat should be synchronous, with no
new call until the previous is processed and I also agree that the async RPC
support is needed to process other important messages. This solves the graceful
degradation issue. What I am saying is that once 100000 mappers send these
heartbeats and wait for them, there will be a delay processing them due to the
server bottleneck, so the metric would reach the client later, unless we
minimize the delay with either a server to client approach or a dynamic
heartbeat interval.
> 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: Haibo Chen
> 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.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
---------------------------------------------------------------------
To unsubscribe, e-mail: mapreduce-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: mapreduce-issues-h...@hadoop.apache.org
