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https://issues.apache.org/jira/browse/ZOOKEEPER-2164?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17047345#comment-17047345
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Mate Szalay-Beko edited comment on ZOOKEEPER-2164 at 2/28/20 11:54 AM:
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Strange... the client connections should not have anything to do to this fix,
we only fix the leader election here. After restart / leader election success,
can you connect to the cluster using e.g. ZooKeeper CLI? For me that worked. If
that works, then I think it will be some other issue (e.g. related to Curator /
NiFi potentially?). Even if the bug seems to be in the ZooKeeper client code,
then I suggest to open a separate ticket for it, because this ticket is about
the leader election.
Can you check the client logs / ZooKeeper server logs? Maybe there are some
hints why NiFi can not re-connect using Curator.
I am not familiar with Curator / NiFi unfortunately... but I am happy to check
what is happening, if you can help me somehow to reproduce it.
was (Author: symat):
Strange... the client connections should not have anything to do to this fix,
we only fix the leader election here. After restart / leader election success,
can you connect to the cluster using e.g. ZooKeeper CLI? For me that worked. If
that works, then I think it will be some other issue (e.g. related to Curator /
NiFi potentially?)
Can you check the client logs / ZooKeeper server logs? Maybe there are some
hints why NiFi can not re-connect using Curator.
I am not familiar with Curator / NiFi unfortunately...
> 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
> Assignee: Mate Szalay-Beko
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.7.0, 3.5.8
>
> Time Spent: 5.5h
> Remaining Estimate: 0h
>
> 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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