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From Michael Dürig (JIRA) <j...@apache.org>
Subject [jira] [Commented] (OAK-4105) Implement FileStore.size through FileStore.approximateSize
Date Wed, 20 Jul 2016 10:34:20 GMT

    [ https://issues.apache.org/jira/browse/OAK-4105?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15385653#comment-15385653
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Michael Dürig commented on OAK-4105:
------------------------------------

TBH I find this 10% error a bit concerning. This means that the main consumer of approximate
size (disk space monitoring {{checkDiskSpace()}}) is also based on bogus information. 

Maybe we should take an entirely different approach: 
* remove {{approximateSize}} again
* reduce the lock surface of the {{size()}} method. This should be simple enough by creating
a copy of the readers / writer inside the lock and do the actual size calculation on that
snapshot but outside of the lock.

In that case I would resolve this issue as won't fix and start with a fresh issue. 

[~frm], WDYT?



> Implement FileStore.size through FileStore.approximateSize
> ----------------------------------------------------------
>
>                 Key: OAK-4105
>                 URL: https://issues.apache.org/jira/browse/OAK-4105
>             Project: Jackrabbit Oak
>          Issue Type: Technical task
>          Components: segment-tar
>            Reporter: Michael Dürig
>            Assignee: Andrei Dulceanu
>            Priority: Minor
>              Labels: resilience
>             Fix For: Segment Tar 0.0.6
>
>         Attachments: OAK-4105-01.patch, OAK-4105-02.patch
>
>
> {{FileStore.size()}} is prone to lock contention and should not be called too often.
As OAK-2879 already introduced an approach for tracking the current size of the file store
without having to lock, we might as well promote his to be "the official" implementation.

> [~frm] WDYT?



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