[jira] [Created] (ZOOKEEPER-1886) Exception in Follower.followLeader() where Leader is still running, can make that follower hang in LeaderElection

["Vinayakumar B (JIRA)" <ji...@apache.org>]

Vinayakumar B created ZOOKEEPER-1886:
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             Summary: Exception in Follower.followLeader() where Leader is still running, can make that follower hang in LeaderElection
                 Key: ZOOKEEPER-1886
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1886
             Project: ZooKeeper
          Issue Type: Bug
          Components: server
            Reporter: Vinayakumar B


SocketTimeoutException in {{Follower#followLeader()}} where the leader is successfully running can make this follower not able to rejoin the quorum.

Analysis:
1. SocketTimeoutException in below code, will make follower to stop following (Not process shutdown) and try to participate in leader election again. 
{code}                while (self.isRunning()) {
                    readPacket(qp);
                    processPacket(qp);
                }{code}

2. At the time of leader election {{FastLeaderElection#logicalclock}} will be incremented at only follower side, and this is more than electionEpoch of the leader.

3. Notification from the Leader will get ignored and from this follower notifications will be continously sent and again ignored.





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