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Posted to dev@zookeeper.apache.org by "Michi Mutsuzaki (JIRA)" <ji...@apache.org> on 2015/04/14 09:36:13 UTC

[jira] [Created] (ZOOKEEPER-2164) fast leader election keeps failing

Michi Mutsuzaki created ZOOKEEPER-2164:
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             Summary: fast leader election keeps failing
                 Key: ZOOKEEPER-2164
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2164
             Project: ZooKeeper
          Issue Type: Bug
          Components: leaderElection
    Affects Versions: 3.4.5
            Reporter: Michi Mutsuzaki


I have a 3-node cluster with sids 1, 2 and 3. Originally 2 is the leader. When I shut down 2, 1 and 3 keep going back to leader election. Here is what seems to be happening.

- Both 1 and 3 elect 3 as the leader.
- 1 receives votes from 3 and itself, and starts trying to connect to 3 as a follower.
- 3 doesn't receive votes for 5 seconds because connectOne() to 2 doesn't timeout for 5 seconds: https://github.com/apache/zookeeper/blob/41c9fcb3ca09cd3d05e59fe47f08ecf0b85532c8/src/java/main/org/apache/zookeeper/server/quorum/QuorumCnxManager.java#L346
- By the time 3 receives votes, 1 has given up trying to connect to 3: https://github.com/apache/zookeeper/blob/41c9fcb3ca09cd3d05e59fe47f08ecf0b85532c8/src/java/main/org/apache/zookeeper/server/quorum/Learner.java#L247

I'm using 3.4.5, but it looks like this part of the code hasn't changed for a while, so I'm guessing later versions have the same issue.



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