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https://issues.apache.org/jira/browse/CURATOR-653?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zili Chen closed CURATOR-653.
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Resolution: Fixed
master via 9b3a145372d9a8bc9a71adb630a1ad9b71fd2889
> Double leader for LeaderLatch
> -----------------------------
>
> Key: CURATOR-653
> URL: https://issues.apache.org/jira/browse/CURATOR-653
> Project: Apache Curator
> Issue Type: Task
> Components: Recipes
> Reporter: Zili Chen
> Assignee: Zili Chen
> Priority: Major
> Fix For: 5.4.0
>
> Time Spent: 2h 40m
> Remaining Estimate: 0h
>
> Reported by @woaishixiaoxiao:
> When I use the LeaderLatch to select leader, there is a double-leader
> phenomenon.
> The timeline is as follows：
> 1. The zk cluster switch leader node bescause of zxid overflow. The cluster
> is unavailable to the outside world
> 2. A client(not leader befor zxid overflow) and B client(is leader before
> zxid overflow) enter the suspend state, B client set its leader status to
> false
> 3. The zk cluster complete the leader node election and the cluster back to
> normal
> 4. A client enter the reconnect state and call the reset function, set its
> leader status to false.
> 5. B client enter the reconnect state, call the reset function. set its
> leader status to false. Delete its old path.
> 6. A client receive preNodeDeleteEvent. Then getChildren from zkServer.
> Find itself is the smallest number and set itself as a leader.
> 7. B client create a new temporary node and then getChildren from zkServer.
> Find itself not the node with the smallest serial number and listen to the
> previous node delete event.
> 8. A client delete its old path.
> 9. B client receive the preNodeDeleteEvent. then getchildren from zkServer.
> Find itself is the smallest sequence number and then set itself as a leader
> 10. A client create a new temporary node and then getChildren from
> zkServer. Find itself not the node with the smallest serial number and
> listen to the previous node delete event. but it doesn't set itself as a
> non-leader state. because of the sixth step operation, A still is leader
> state now.
> 11. now A client and B client are the leader at the same time
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