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https://issues.apache.org/jira/browse/MAPREDUCE-3730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13194902#comment-13194902
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Jason Lowe commented on MAPREDUCE-3730:
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bq. Also, instead of using a new RMNodeImpl, you can simply send a RECONNECTED
event to the existing RMNodeImpl.
There are a few reasons I thought using a new RMNodeImpl would be better:
1) The new node could have different capabilities than the previous node (e.g.:
more RAM).
2) Reusing the node means all states have to handle the RECONNECTED event. It
seemed simpler from a maintenance standpoint to treat the RECONNECTED event as
an accelerated EXPIRE/STARTED transition since that's effectively what
occurred. The RM just didn't get a chance to notice the EXPIRE event because
the timeout was too large in that instance.
bq. I think we should also not process the health status during registration.
That will happen anyways in the next status update, right?
Following the "accelerated EXPIRE/STARTED" logic, it seemed better to assume a
reconnected node is just like a newly connected node (i.e.: we assume healthy
until proven otherwise). As you say, any incorrect guess there will be
corrected on the next status update.
> Allow restarted NM to rejoin cluster before RM expires it
> ---------------------------------------------------------
>
> Key: MAPREDUCE-3730
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3730
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: mrv2, resourcemanager
> Affects Versions: 0.23.1, 0.24.0
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Attachments: MAPREDUCE-3730.patch, MAPREDUCE-3730.patch
>
>
> When a node in the RUNNING state (healthy or unhealthy) is rebooted, the
> resourcemanager rejects the nodemanager's registration request as a duplicate
> because it is convinced that the nodemanager is already running on that node.
> It won't allow that node to rejoin the cluster until the node expiration
> time elapses which is 10min+ by default. We should allow the NM to rejoin
> the cluster if it re-registers within the expiration timeout.
> Note that this problem occurs with NMs that are configured to specific ports.
> If ephemeral ports are used then a NM reboot "works" because the RM thinks
> the NM registration is for a new node. See the discussions in MAPREDUCE-3070
> and MAPREDUCE-3363.
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