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From "Pavel Pervov (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HARMONY-5040) [drlvm][classloader] Java field ordering must be preserved
Date Fri, 09 Nov 2007 14:27:53 GMT

     [ https://issues.apache.org/jira/browse/HARMONY-5040?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Pavel Pervov updated HARMONY-5040:
----------------------------------

    Attachment: fo-stable-1.patch

This is the easiest part. :) Here it goes.

Two vm properties are added: vm.sort_fields and vm.compact_fields.

Initially I had an idea of adding one more switch which includes turning them both on, but
I couldn't think of the right name for such a property.

> [drlvm][classloader] Java field ordering must be preserved
> ----------------------------------------------------------
>
>                 Key: HARMONY-5040
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5040
>             Project: Harmony
>          Issue Type: Improvement
>          Components: DRLVM
>            Reporter: Aleksey Shipilev
>         Attachments: fo-stable-1.patch, fo-stable-1.patch, fo-stable-1.patch
>
>
> Current implementation of class support in Harmony sorts the class fields decrementally
by size to avoid misalignment. However, it's done with quicksort which is known to be unstable
(e.g. there are no guarantees that order of elements with equal keys will not be changed).
That lead to shaking Java field order which could be optimized to achieve the spatial locality.

> Proposed patch changes the sorting algorithm to bubblesort, which is known to be stable.
That's performance-safe since average field count is not high.

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