[jira] [Commented] (ZOOKEEPER-2988) NPE triggered if server receives a vote for a server id not in their voting view

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16432600#comment-16432600 ] 

ASF GitHub Bot commented on ZOOKEEPER-2988:
-------------------------------------------

Github user enixon commented on the issue:

    https://github.com/apache/zookeeper/pull/476
  
    @maoling I was about 2/3 done with cleaning up this diff when I got dragged into different projects. Thanks for the ping, I'll try to update here this week.


> NPE triggered if server receives a vote for a server id not in their voting view
> --------------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-2988
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2988
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: leaderElection
>    Affects Versions: 3.5.3, 3.4.11
>            Reporter: Brian Nixon
>            Priority: Minor
>
> We've observed the following behavior in elections when a node is lagging behind the quorum in its view of the ensemble topology.
> - Node A is operating with node B in its voting view, but without view of node C.
> - B votes for C.
> - A then switches its vote to C, but throws a NPE when attempting to connect.
> This causes the QuorumPeer to spin up a Follower only to immediately have it shutdown by the exception.
> Ideally, A would not advertise a vote for a server that it will not follow.



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