[jira] [Assigned] (OAK-6483) Segment-based composite node store performance degradation

["Tomek Rękawek (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OAK-6483?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tomek Rękawek reassigned OAK-6483:
----------------------------------

    Assignee: Tomek Rękawek

> Segment-based composite node store performance degradation
> ----------------------------------------------------------
>
>                 Key: OAK-6483
>                 URL: https://issues.apache.org/jira/browse/OAK-6483
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: composite
>    Affects Versions: 1.7.4
>            Reporter: Tomek Rękawek
>            Assignee: Tomek Rękawek
>            Priority: Critical
>             Fix For: 1.8, 1.7.5
>
>
> It seems that the OAK-4732 is not compatible with the composite node store using a segment node store as the main (writeable) store. The OAK-4732 measures how much does it usually take to apply commit hooks and merge the new root. However, the composite node store plugs into the commit hook and reads other node store states. As a result, it may take quite a while and the measured values are big. They are then used to tune the lock inside the LockBasedScheduler#getHeadNodeState() method. Since the times are big, the method also waits a long time for the semaphore before it gives up. This causes performance degradation.
> The {{-Doak.scheduler.fetch.commitDelayQuantile=0}} parameter can be used to disable the OAK-4732.



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