[jira] [Comment Edited] (OAK-2682) Introduce time difference detection for DocumentNodeStore

["Chetan Mehrotra (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-2682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14484775#comment-14484775 ] 

Chetan Mehrotra edited comment on OAK-2682 at 4/8/15 6:04 AM:
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It would be a good feature to have however I am not sure if the solution can be stable (i.e. not produce noise) without a peer to peer communication. The problem being solved is similar to what NTP solves so I would prefer to leave that to NTP. Probably have a Java NTP Client [1] or if to be more self sufficient embed a NTP server.

Have not thought through the solution so may be I am wrong here. But given other issues I would consider this a low priority one IMO. Further in most cases production system do have NTP synchronization enabled and I have not seen this being a recurrent problem so far. 

My 2 cents!

[1] https://github.com/apache/directory-server/tree/trunk/protocol-ntp


was (Author: chetanm):
It would be a good feature to have however I am not sure if the solution can be stable (i.e. not produce noise) without a peer to peer communication. The problem being solved is similar to what NTP solves so I would prefer to leave that to NTP. Probably have a Java NTP Client [1] or if to be more self sufficient embed a NTP server.

Have not thought through the solution but may be I am wrong here.

[1] https://github.com/apache/directory-server/tree/trunk/protocol-ntp

> 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
>             Fix For: 1.3.0
>
>
> 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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