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https://issues.apache.org/jira/browse/ZOOKEEPER-366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13070960#comment-13070960
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Mahadev konar commented on ZOOKEEPER-366:
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Chang,
I probably wont have time over the next few weeks to fix this (given the 3.4
release). Please feel free to take it over or if someone else wants to fix it,
he/she is welcome to do so.
> 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.
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