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https://issues.apache.org/jira/browse/ZOOKEEPER-366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12932809#action_12932809
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Benjamin Reed commented on ZOOKEEPER-366:
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i haven't had a chance to get back to this. we really need to convert all the
currentTimeMillis() to nanoTime(). we need to do a similar change in the C
client.
i don't think we can do a test for this.
> 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: 3.3.3, 3.4.0
>
> 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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