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https://issues.apache.org/jira/browse/ZOOKEEPER-1912?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tanakorn Leesatapornwongsa updated ZOOKEEPER-1912:
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Attachment: log.zip
conf.zip
Attach log files and config files
> Leader election lets 2 leaders happen
> -------------------------------------
>
> Key: ZOOKEEPER-1912
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1912
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection
> Affects Versions: 3.4.6
> Environment: Ubuntu 12.04, OpenJDK 1.6
> Reporter: Tanakorn Leesatapornwongsa
> Priority: Minor
> Attachments: conf.zip, log.zip
>
>
> In 3-node cluster, when there are 2 nodes die and reboot during leader
> election, it might lead to the case that there are 2 leaders happen in the
> system. Eventually, a leader that does not has follower supports and quit
> being leader, but it makes us lose some availability.
> I am building a tools that can reorder messages and disk write, and also
> inject node crash to the system and found this bug.
> These are the step of events that lead to 2 leaders at the end. My zookeeper
> nodes have id = 0,1,2
> packetsend from=0 to=1 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=0 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=2 to=0 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=2 to=1 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=1 to=0 state=0 leader=1 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=1 to=2 state=0 leader=1 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=1 to=0 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=0 to=1 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=1 to=2 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=0 to=2 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> diskwrite nodeId=0 write=currentEpoch
> nodecrash id=0
> nodecrash id=1
> nodestart id=0
> nodestart id=1
> diskwrite nodeId=2 write=currentEpoch
> packetsend from=2 to=0 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=0 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=0 leader=2 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=0 to=1 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=1 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=1 to=2 state=0 leader=1 zxid=0 electionEpoch=1 peerEpoch=0
> packetsend from=2 to=0 state=2 leader=2 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=2 leader=2 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=2 leader=2 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=0 to=1 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=2 leader=2 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=0 to=1 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=2 leader=2 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=1 to=2 state=0 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=0 to=1 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=0 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=2 to=1 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=0 to=2 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=0 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=1 to=0 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=1 to=2 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=2 to=1 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=0 to=2 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=0 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=0 to=1 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> packetsend from=2 to=1 state=0 leader=2 zxid=0 electionEpoch=2 peerEpoch=1
> packetsend from=0 to=2 state=2 leader=0 zxid=0 electionEpoch=1 peerEpoch=1
> diskwrite nodeId=2 write=currentEpoch
> diskwrite nodeId=1 write=currentEpoch
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