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From "Thomas Mueller (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JCR-1112) CacheManager interval between recalculation of cache sizes should be configurable
Date Tue, 25 Sep 2007 09:55:51 GMT

    [ https://issues.apache.org/jira/browse/JCR-1112?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12530078
] 

Thomas Mueller commented on JCR-1112:
-------------------------------------

Hi,

The method getMemoryUsed could be improved by keeping the current value and only add / subtract
when there are changes. Still from time to time a full recalculation (like now) is required
because the size of the objects in the cache could change. If only one in 20 calls trigger
a full recalculation, it would result in a speed up of about 10 times.

For me, the CacheManager is a workaround; if possible the number of caches should be reduced
to one.

Thomas

> CacheManager interval between recalculation of cache sizes should be configurable
> ---------------------------------------------------------------------------------
>
>                 Key: JCR-1112
>                 URL: https://issues.apache.org/jira/browse/JCR-1112
>             Project: Jackrabbit
>          Issue Type: New Feature
>          Components: jackrabbit-core
>            Reporter: Przemo Pakulski
>            Assignee: Thomas Mueller
>            Priority: Minor
>         Attachments: JCR-1112.txt
>
>
> Currently interval between recaluclation of cahce size is hard coded to 1000 ms. Resizing/recalculation
of cache size is quite expensive method (especially getMemoryUsed on MLRUItemStateCache is
time consuming)
> Depending on the configuration, we realized that under some load up to 10-15% percent
of CPU time (profiler metrics) could be spend doing such recalculations. It does not seem
to be needed to resize cache every second. Best this interval should be configurable in external
config. file with other cache settings (like memory sizes).

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