You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@zookeeper.apache.org by "Ted Dunning (Commented) (JIRA)" <ji...@apache.org> on 2012/01/24 02:03:40 UTC
[jira] [Commented] (ZOOKEEPER-366) Session timeout detection can go
wrong if the leader system time changes
[ https://issues.apache.org/jira/browse/ZOOKEEPER-366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13191711#comment-13191711 ]
Ted Dunning commented on ZOOKEEPER-366:
---------------------------------------
History repeats itself. I have patches on ZOOKEEPER-1366 that use nanoTime to avoid these problems, but don't include the limit on number of expirations per tick.
I suggest that we mark this issue as a duplicate of that issue and apply that patch since it is up to date. Any objections?
> Session timeout detection can go wrong if the leader system time changes
> ------------------------------------------------------------------------
>
> Key: ZOOKEEPER-366
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-366
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum, server
> Reporter: Benjamin Reed
> Assignee: Benjamin Reed
> Fix For: 3.5.0
>
> Attachments: ZOOKEEPER-366.patch
>
>
> the leader tracks session expirations by calculating when a session will timeout and then periodically checking to see what needs to be timed out based on the current time. this works great as long as the leaders clock progresses at a steady pace. the problem comes when there are big (session size) changes in clock, by ntp for example. if time gets adjusted forward, all the sessions could timeout immediately. if time goes backward sessions that should timeout may take a lot longer to actually expire.
> this is really just a leader issue. the easiest way to deal with this is to have the leader relinquish leadership if it detects a big jump forward in time. when a new leader gets elected, it will recalculate timeouts of active sessions.
--
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