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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 Sun, 30 Mar 2008 15:05:24 GMT

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

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

    Derby Info:   (was: [Patch Available])

Committed d2911-14.diff with revision 642752.
Committed d2911-15.diff with revision 642755.

I think all comments have been addressed now, and I'm not planning any more patches on this
issue. Some of the patches have only been committed to trunk (revisions 635577, 636247, 636670,
642752 and 642755). None of them needs to go to the 10.4 branch, but unless there are objections,
I'll merge them to minimize the difference between trunk and the branch (which makes it easier
to map stack traces from bug reports against 10.4 to the code in trunk).

> 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, d2911-12.diff, d2911-13.diff, d2911-14.diff, d2911-15.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-enable.diff, 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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