[jira] [Commented] (OAK-4528) diff calculation in DocumentNodeStore should try to re-use journal info on diff cache miss

["Marcel Reutegger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-4528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15376510#comment-15376510 ] 

Marcel Reutegger commented on OAK-4528:
---------------------------------------

Implemented in trunk: http://svn.apache.org/r1752596

There is a feature flag {{-Doak.disableJournalDiff=true}} to disable diff calculation based on the journal. The fallback is the previous implementation.

I will perform some more tests before I resolve this issue.

> diff calculation in DocumentNodeStore should try to re-use journal info on diff cache miss
> ------------------------------------------------------------------------------------------
>
>                 Key: OAK-4528
>                 URL: https://issues.apache.org/jira/browse/OAK-4528
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: core, documentmk
>            Reporter: Vikas Saurabh
>            Assignee: Marcel Reutegger
>            Priority: Minor
>              Labels: observation, resilience
>             Fix For: 1.6
>
>
> Currently, diff information is filled into caches actively (local commits pushed in local_diff, externally read changes pushed into memory_diff). At the time of event processing though, the entries could have already been evicted.
> In that case, we fall back to computing diff by comparing 2 node-states which becomes more and more expensive (and eventually fairly non-recoverable leading to OAK-2683).
> To improve the situation somewhat, we can probably try to consult journal entries to read a smaller-superset of changed paths before falling down to comparison.
> /cc [~mreutegg], [~chetanm], [~egli]



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