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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5772) Give users a way to monitor more Derby internals.
Date Tue, 02 Sep 2014 08:39:23 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5772?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-5772:
--------------------------------------
    Attachment: pagecache-counters.diff

The attached patch [^pagecache-counters.diff] shows how one might add an MBean that lets you
monitor hit count, miss count and eviction count for the page cache via JMX.

It's just an example. A complete patch would have to make the MBean check that SystemPermission("engine",
"monitor") is granted before returning any data, it would need functional tests, and we should
also run performance tests to verify that the counters don't add any noticeable overhead.

> Give  users a way to monitor more Derby internals.
> --------------------------------------------------
>
>                 Key: DERBY-5772
>                 URL: https://issues.apache.org/jira/browse/DERBY-5772
>             Project: Derby
>          Issue Type: Improvement
>          Components: JMX, Tools
>    Affects Versions: 10.9.1.0
>            Reporter: Rick Hillegas
>         Attachments: pagecache-counters.diff
>
>
> We should give users a way to track hits/misses in the page cache. This will help users
tune the size of the page cache. JMX-visible monitors might be a useful solution here. See
the following email thread: http://old.nabble.com/Cache-Hit-Miss-rates-for-Derby-pageCache-to33865646.html#a33865646



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