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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3731) Improve calculation of refSize in ClassSize.java
Date Wed, 23 Jul 2008 12:47:32 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12615999#action_12615999
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Kristian Waagan commented on DERBY-3731:
----------------------------------------

Thanks for looking at the patch, Knut Anders.
Your comments are all valid, I'll incorporate them in the next revision.

I investigated a little more regarding the permissions. Seems Derby isn't allowed to read
sun.arch.data.model with the current policy file, but it is allowed to read os.arch for some
reason.
Adding code to print the current permissions shows that reading the property os.arch is indeed
granted, but it is not in our default policy file. Since I don't know if this is specific
for the Sun JVM or not, maybe we should document and add both permissions to the default policy
file?

> 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
>            Priority: Minor
>         Attachments: derby-3731-1a-refsize_from_properties.diff, 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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