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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3731) Improve calculation of refSize in ClassSize.java
Date Thu, 24 Jul 2008 10:35:32 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12616439#action_12616439
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Kristian Waagan commented on DERBY-3731:
----------------------------------------

Thanks for the testing, Knut Anders.

Yes, catching the NFE should be done. I have found out that the property can be set to "unknown".
I'm also wondering if we should enforce 4 and 8 as return values to avoid any surprises on
"exotic VMs".

> Improve calculation of refSize in ClassSize.java 
> -------------------------------------------------
>
>                 Key: DERBY-3731
>                 URL: https://issues.apache.org/jira/browse/DERBY-3731
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>            Reporter: Kathey Marsden
>            Assignee: Kristian Waagan
>            Priority: Minor
>         Attachments: derby-3731-1a-refsize_from_properties.diff, derby-3731-1b-refsize_from_properties.diff,
derby-3731-1b-refsize_from_properties.stat, DERBY-3731_diff.txt
>
>
> java/engine/org/apache/derby/iapi/services/cache/ClassSize.java has a static code block
which calculates the size of a reference for the architecture.  This code could be improved
by adding garbage collection before measuring memory, to give a consistent  reading.     Also
there have been suggestions that we use os.arch or sun.arch.data.model to make the measurement
more reliable, especially on 64bit machines.

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