[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=16382603#comment-16382603 ] 

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

GitHub user enixon opened a pull request:

    https://github.com/apache/zookeeper/pull/476

    ZOOKEEPER-2988: NPE triggered if server receives a vote for a server …

    …id not in their voting view

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/enixon/zookeeper ZOOKEEPER-2988

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/zookeeper/pull/476.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #476
    
----
commit 1862a718168ee07287d0b9769a0f4ce20bd1bd32
Author: Brian Nixon <ni...@...>
Date:   2018-03-01T19:19:51Z

    ZOOKEEPER-2988: NPE triggered if server receives a vote for a server id not in their voting view

----


> 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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