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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3092) Use java.util.concurrent in TransactionTable to improve scalability
Date Wed, 20 Jan 2010 09:14:58 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3092?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Knut Anders Hatlen updated DERBY-3092:

    Attachment: derby-3092-2a-count.diff

I was a little too aggressive in trimming down the code in the previous patch. In writeExternal()
there used to be an "if (count > 0)" surrounding the second for loop, and it got removed
by the 1b patch. This is just a tiny optimization that prevents a second scan of the transaction
table if it only contains read-only transactions, so its removal should not cause any harm.
But it was not supposed to be removed, so here's another patch (2a) that adds it back.

> Use java.util.concurrent in TransactionTable to improve scalability
> -------------------------------------------------------------------
>                 Key: DERBY-3092
>                 URL: https://issues.apache.org/jira/browse/DERBY-3092
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions:
>            Reporter: Dyre Tjeldvoll
>            Assignee: Knut Anders Hatlen
>         Attachments: derby-3092-1a-map.diff, derby-3092-1b-map.diff, derby-3092-2a-count.diff,
xact-concept.diff, xact-concept.png
> Running scalability tests with the client and buffer manager from DERBY-2911 shows that
access to the TransactionTable.trans (a Hashtable) and XactFactory.tranId (a shared long)
are the next major sources of contention. 

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