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From "Michael Han (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (ZOOKEEPER-3479) Logging false leader election times
Date Fri, 02 Aug 2019 04:12:00 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-3479?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Michael Han reassigned ZOOKEEPER-3479:
--------------------------------------

    Assignee: Karolos Antoniadis

> Logging false leader election times
> -----------------------------------
>
>                 Key: ZOOKEEPER-3479
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3479
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: leaderElection
>    Affects Versions: 3.5.5
>            Reporter: Karolos Antoniadis
>            Assignee: Karolos Antoniadis
>            Priority: Minor
>              Labels: pull-request-available
>         Attachments: server1.txt, server2.txt
>
>          Time Spent: 2h 20m
>  Remaining Estimate: 0h
>
> There seems to be a problem with the logging of leader election times: the logged times
are much smaller than the actual time it took for the leader election to complete.
> This bug can be easily reproduced by following these steps:
> 1) Run a ZK cluster of 3 servers
> 2) Kill the server that is currently the leader
> 3) The log files of the remaining 2 servers contain false leader election times
>  
> In the attached files you can see the log files of the remaining 2 serve. For brevity,
I removed the parts before and after the leader election from the log files.
> For example, in {{server1.txt}} we can see that:
>  
> {code:java}
> 2019-07-31 00:57:31,852 [myid:1] - WARN [QuorumPeer[myid=1](plain=/0.0.0.0:2791)(secure=disabled):QuorumPeer@1318]
- PeerState set to LOOKING
> 2019-07-31 00:57:31,853 [myid:1] - INFO [QuorumPeer[myid=1](plain=/0.0.0.0:2791)(secure=disabled):QuorumPeer@1193]
- LOOKING
> 2019-07-31 00:57:31,853 [myid:1] - INFO [QuorumPeer[myid=1](plain=/0.0.0.0:2791)(secure=disabled):FastLeaderElection@885]
- New election. My id = 1, proposed zxid=0x100000001
> [...]
> 2019-07-31 00:57:32,272 [myid:1] - INFO [QuorumPeer[myid=1](plain=/0.0.0.0:2791)(secure=disabled):Follower@69]
- FOLLOWING - LEADER ELECTION TOOK - 1 MS{code}
> Leader election supposedly took only 1ms, but in reality it took (32,272 - 31,853) =
419ms!
> The reason for this bug seems to be the introduction of this line
> {code:java}
> start_fle = Time.currentElapsedTime();{code}
> (seen here [https://github.com/apache/zookeeper/blob/master/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumPeer.java#L1402]) 
> back in this commit [https://github.com/apache/zookeeper/commit/5428cd4bc963c2e653a260c458a8a8edf3fa08ef].
>  
>  
>  
>  



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