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Rohith Sharma K S commented on YARN-6102:
-----------------------------------------
I think there are 2 solution to solve this issue.
# Ensure RPC threads are stopped. This would be expensive where in every thread need to join
or any other mechanism.
# How about recreating RMContext for each transition? This allows to take always new context
and deal with it. cc :/ [~jianhe]
> On failover RM can crash due to unregistered event to AsyncDispatcher
> ---------------------------------------------------------------------
>
> Key: YARN-6102
> URL: https://issues.apache.org/jira/browse/YARN-6102
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 2.8.0, 2.7.3
> Reporter: Ajith S
> Assignee: Ajith S
> Priority: Critical
> Attachments: eventOrder.JPG
>
>
> {code}2017-01-17 16:42:17,911 FATAL [AsyncDispatcher event handler] event.AsyncDispatcher
(AsyncDispatcher.java:dispatch(200)) - Error in dispatcher thread
> java.lang.Exception: No handler for registered for class org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNodeEventType
> at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:196)
> at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:120)
> at java.lang.Thread.run(Thread.java:745)
> 2017-01-17 16:42:17,914 INFO [AsyncDispatcher ShutDown handler] event.AsyncDispatcher
(AsyncDispatcher.java:run(303)) - Exiting, bbye..{code}
> The same stack i was also noticed in {{TestResourceTrackerOnHA}} exits abnormally, after
some analysis, i was able to reproduce.
> Once the nodeHeartBeat is sent to RM, inside {{org.apache.hadoop.yarn.server.resourcemanager.ResourceTrackerService.nodeHeartbeat(NodeHeartbeatRequest)}},
before sending it to dispatcher through
> {{this.rmContext.getDispatcher().getEventHandler().handle(nodeStatusEvent);}} if RM failover
is called, the dispatcher is reset
> The new dispatcher is however first started and then the events are registered at {{org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.reinitialize(boolean)}}
> So event order will look like
> 1. Send Node heartbeat to {{ResourceTrackerService}}
> 2. In {{ResourceTrackerService.nodeHeartbeat}}, before passing to dispatcher call RM
failover
> 3. In RM Failover, current active will reset dispatcher @reinitialize i.e ( {{resetDispatcher();}}
+ {{createAndInitActiveServices();}} )
> Now between {{resetDispatcher();}} and {{createAndInitActiveServices();}} , the {{ResourceTrackerService.nodeHeartbeat}}
invokes dipatcher
> This will cause the above error as at point of time when {{STATUS_UPDATE}} event is given
to dispatcher in {{ResourceTrackerService}} , the new dispatcher(from the failover) may be
started but not yet registered for events
> Using same steps(with pausing JVM at debug), i was able to reproduce this in production
cluster also. for {{STATUS_UPDATE}} active service event, when the service is yet to forward
the event to RM dispatcher but a failover is called and dispatcher reset is between {{resetDispatcher();}}
& {{createAndInitActiveServices();}}
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