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https://issues.apache.org/jira/browse/OAK-2682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14680020#comment-14680020
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Stefan Egli commented on OAK-2682:
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bq. So are you asking for the difference between the system clocks of the local
machine and the machine on which the database runs?
yes, exactly. The (simple) cluster time difference detection is as follows:
* each machine checks to have the clock within a certain margin in sync with
the server
* if one machine does not: it shall complain very loudly and stop functioning
* given the above all machines have their clocks in sync with a maximum offset
of 2 * margin_with_server.
* which gives us an easy enough cluster-internal time difference detection
(without going into too much trying to be 'NTP-style')
> Introduce time difference detection for DocumentNodeStore
> ---------------------------------------------------------
>
> Key: OAK-2682
> URL: https://issues.apache.org/jira/browse/OAK-2682
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: core, mongomk
> Reporter: Stefan Egli
> Assignee: Stefan Egli
> Labels: resilience
> Fix For: 1.3.5
>
> Attachments: OAK-2682.patch
>
>
> Currently the lease mechanism in DocumentNodeStore/mongoMk is based on the
> assumption that the clocks are in perfect sync between all nodes of the
> cluster. The lease is valid for 60sec with a timeout of 30sec. If clocks are
> off by too much, and background operations happen to take couple seconds, you
> run the risk of timing out a lease. So introducing a check which WARNs if the
> clocks in a cluster are off by too much (1st threshold, eg 5sec?) would help
> increase awareness. Further drastic measure could be to prevent a startup of
> Oak at all if the difference is for example higher than a 2nd threshold
> (optional I guess, but could be 20sec?).
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