Karolos Antoniadis created ZOOKEEPER-3479:
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Summary: 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
Attachments: server1.txt, server2.txt
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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