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https://issues.apache.org/jira/browse/ZOOKEEPER-1209?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13121034#comment-13121034
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Rakesh R commented on ZOOKEEPER-1209:
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Hi,
I have attached the initial patch (with test cases) which will make the client
node to 'neutral' mode after disconnection and stop after session expiration,
rather than in Elected mode.
The attached patch tries to handle Syncconnected, Disconnected, Expired
connection events.
Any review help would be appreciated..
Thanks,
Rakesh
> LeaderElection recipe doesn't handle the split-brain issue, n/w disconnection
> can bring both the client nodes to be in ELECTED
> ------------------------------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-1209
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1209
> Project: ZooKeeper
> Issue Type: Bug
> Components: recipes
> Affects Versions: 3.3.3
> Reporter: Rakesh R
> Assignee: Rakesh R
> Attachments: ZOOKEEPER-1209.patch
>
>
> *Case1-* N/w disconnection can bring both the client nodes to be in ELECTED
> state. Current LeaderElectionSupport(LES) f/w handles only 'NodeDeletion'.
>
> Consider the scenario where ELECTED and READY nodes are running. Say ELECTED
> node's n/w got failed and is "Disconnected" from ZooKeeper. But it will
> behave as ELECTED as it is not getting any events from the
> LeaderElectionSupport(LES) framework.
> After sessiontimeout, node in READY state will be notified by 'NodeDeleted'
> event and will go to ELECTED state.
> *Problem:*
> Both the node becomes ELECTED and finally the user sees two Master (ELECTED)
> node and cause inconsistencies.
> *Case2-* Also in this case, Let's say if user has started only one client
> node and becomes ELECTED. After sometime n/w has disconnected with the
> ZooKeeper server and the session got expired.
> *Problem:*
> Still the client node will be in the ELECTED state. After sometime if user
> has started the second client node. Again both the nodes becomes ELECTED.
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