[
https://issues.apache.org/jira/browse/ZOOKEEPER-1514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13426138#comment-13426138
]
Flavio Junqueira commented on ZOOKEEPER-1514:
---------------------------------------------
bq. I don't really mind the check, it's just completely unnecessary (since
listener == null => NPE => failed test). Let's keep it in if you think it is
important.
Sounds fine, I'll remove the check from both tests and upload a new patch.
bq. What is a problem, and I agree not worth fixing here, is that this is yet
another example of class members not being hidden behind getters / setters that
maintain correct invariants. Anyone can set listener to null, because it's a
non-final public member, so every read of that variable in code that mustn't
crash has to defensively check that it's not null, when we should be relying on
the class to do this for us.
I totally agree. I think we did not expect the listener object to be called in
multiple places and were a bit lazy. :-)
> FastLeaderElection - leader ignores the round information when joining a
> quorum
> -------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-1514
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1514
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum
> Affects Versions: 3.3.4
> Reporter: Patrick Hunt
> Assignee: Flavio Junqueira
> Priority: Critical
> Fix For: 3.4.4, 3.5.0, 3.3.7
>
> Attachments: ZOOKEEPER-1514.patch, ZOOKEEPER-1514.patch,
> ZOOKEEPER-1514.patch
>
>
> In the following case we have a 3 server ensemble.
> Initially all is well, zk3 is the leader.
> However zk3 fails, restarts, and rejoins the quorum as the new leader (was
> the old leader, still the leader after re-election)
> The existing two followers, zk1 and zk2 rejoin the new quorum again as
> followers of zk3.
> zk1 then fails, the datadirectory is deleted (so it has no state whatsoever)
> and restarted. However zk1 can never rejoin the quorum (even after an hour).
> During this time zk2 and zk3 are serving properly.
> Later all three servers are later restarted and properly form a functional
> quourm.
> Here are some interesting log snippets. Nothing else of interest was seen in
> the logs during this time:
> zk3. This is where it becomes the leader after failing initially (as the
> leader). Notice the "round" is ahead of zk1 and zk2:
> {noformat}
> 2012-07-18 17:19:35,423 - INFO
> [QuorumPeer:/0.0.0.0:2181:FastLeaderElection@663] - New election. My id = 3,
> Proposed zxid = 77309411648
> 2012-07-18 17:19:35,423 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 3 (n.leader), 77309411648
> (n.zxid), 832 (n.round), LOOKING (n.state), 3 (n.sid), LOOKING (my state)
> 2012-07-18 17:19:35,424 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 3 (n.leader), 73014444480
> (n.zxid), 831 (n.round), FOLLOWING (n.state), 2 (n.sid), LOOKING (my state)
> 2012-07-18 17:19:35,424 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 3 (n.leader), 73014444480
> (n.zxid), 831 (n.round), FOLLOWING (n.state), 1 (n.sid), LOOKING (my state)
> 2012-07-18 17:19:35,424 - INFO [QuorumPeer:/0.0.0.0:2181:QuorumPeer@655] -
> LEADING
> {noformat}
> zk1 which won't come back. Notice that zk3 is reporting the round as 831,
> while zk2 thinks that the round is 832:
> {noformat}
> 2012-07-18 17:31:12,015 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 1 (n.leader), 77309411648
> (n.zxid), 1 (n.round), LOOKING (n.state), 1 (n.sid), LOOKING (my state)
> 2012-07-18 17:31:12,016 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 3 (n.leader), 73014444480
> (n.zxid), 831 (n.round), LEADING (n.state), 3 (n.sid), LOOKING (my state)
> 2012-07-18 17:31:12,017 - INFO [WorkerReceiver
> Thread:FastLeaderElection@496] - Notification: 3 (n.leader), 77309411648
> (n.zxid), 832 (n.round), FOLLOWING (n.state), 2 (n.sid), LOOKING (my state)
> 2012-07-18 17:31:15,219 - INFO
> [QuorumPeer:/0.0.0.0:2181:FastLeaderElection@697] - Notification time out:
> 6400
> {noformat}
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
