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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-2911) Implement a buffer manager using java.util.concurrent classes
Date Fri, 01 Feb 2008 15:53:10 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-2911:
--------------------------------------

    Attachment: perftest.pdf
                perftest2.diff

I finally got around to look at the results from the tests I had running. Sorry for the delay.

Attached is a diff (perftest2.diff) with an updated version of the performance tests that
I used (the load that were supposed to resemble the d2911perf class attached to this issue,
was changed so that it matched d2911perf more closely, and this change also simplified the
code a bit), and a pdf (perftest.pdf) which summarizes the findings. Nothing new there, actually,
the results were pretty consistent with the results that have been posted here earlier. The
new buffer manager performs significantly better than the old one when there's no other contention
point (like the log device or the root node in the B-tree) and there are multiple CPUs/cores,
and a little better than or equal to the old buffer manager in cases where there is another
contention point.

> 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, d2911-10.diff,
d2911-10.stat, d2911-11.diff, d2911-2.diff, d2911-3.diff, d2911-4.diff, d2911-5.diff, d2911-6.diff,
d2911-6.stat, d2911-7.diff, d2911-7a.diff, d2911-9.diff, d2911-9.stat, d2911-entry-javadoc.diff,
d2911-unused.diff, d2911-unused.stat, d2911perf.java, derby-2911-8.diff, derby-2911-8.stat,
perftest.diff, perftest.pdf, perftest.stat, perftest2.diff, 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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