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https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-2911:
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Attachment: poisson_patch8.tar
poisson_patch8.tar contains the code I used to run Poisson distributed
single-record updates on a 16GB database. It also contains graphs showing the
average response times with derby.storage.pageCacheSize 1000 and 10000,
comparing trunk and ConcurrentCache with patch #8. As predicted by Jørgen, this
test shows more clearly the advantages of the new background cleaner. It seems
clear that the old buffer manager collapse (that is, its response times grow
quickly) at a significantly lower number of requests per second with this load.
> Implement a buffer manager using java.util.concurrent classes
> -------------------------------------------------------------
>
> Key: DERBY-2911
> URL: https://issues.apache.org/jira/browse/DERBY-2911
> Project: Derby
> Issue Type: Improvement
> Components: Performance, Services
> Affects Versions: 10.4.0.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Priority: Minor
> Attachments: cleaner.diff, cleaner.tar, d2911-1.diff, d2911-1.stat,
> d2911-2.diff, d2911-3.diff, d2911-4.diff, d2911-5.diff, d2911-6.diff,
> d2911-6.stat, d2911-7.diff, d2911-7a.diff, d2911-entry-javadoc.diff,
> d2911-unused.diff, d2911-unused.stat, d2911perf.java, derby-2911-8.diff,
> derby-2911-8.stat, perftest6.pdf, poisson_patch8.tar
>
>
> There are indications that the buffer manager is a bottleneck for some types
> of multi-user load. For instance, Anders Morken wrote this in a comment on
> DERBY-1704: "With a separate table and index for each thread (to remove latch
> contention and lock waits from the equation) we (...) found that
> org.apache.derby.impl.services.cache.Clock.find()/release() caused about 5
> times more contention than the synchronization in LockSet.lockObject() and
> LockSet.unlock(). That might be an indicator of where to apply the next push".
> It would be interesting to see the scalability and performance of a buffer
> manager which exploits the concurrency utilities added in Java SE 5.
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