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https://issues.apache.org/jira/browse/DERBY-3092?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-3092:
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Issue & fix info: [Patch Available]
As far as I can see, none of the code that currently synchronizes on the
Hashtable modifies any shared state outside of the Hashtable itself, so the
only purpose of this synchronization appears to be to make the Hashtable
operations atomic. This is also ensured by ConcurrentHashMap, so I've come to
the conclusion that we don't need to add any new synchronization level when we
remove "synchronized (trans)" around the for loops. Setting the Patch Available
flag to record that I think the patch is ready for review.
I will need to run more tests in order to fully convince myself that the
changes are fine. Should we however commit the patch earlier in order to get as
much testing as possible? If it's getting closer to the release date and we
feel that we don't yet have the required level of confidence in the new code,
it could easily be disabled by commenting out a couple of lines in
modules.properties and we would fall back to the old, well-tested code on all
platforms.
> 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: 10.3.1.4
> Reporter: Dyre Tjeldvoll
> Assignee: Knut Anders Hatlen
> Attachments: derby-3092-1a-map.diff, derby-3092-1b-map.diff,
> derby-3092-2a-count.diff, derby-3092-3a-xa-visitor.diff,
> derby-3092-4a-more-visitors.diff, derby-3092-5a-dynamic-loading.diff,
> derby-3092-5a-dynamic-loading.stat, 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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