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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 Tue, 11 Mar 2008 13:28:47 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: d2911-12.diff

Attaching d2911-12.diff which addresses Øystein's comments 3a, 4a (indirectly, since that
code was removed), 4b and 4f. It makes ReplacementPolicy.insertEntry() void since the return
value is not used, it simplifies the handling of small caches in ClockPolicy.rotateClock(),
and it factors out common code in ClockPolicy.rotateClock() and ClockPolicy.shrinkMe(). This
patch is not supposed to change the behaviour in any way.

suites.All ran cleanly. I have also started derbyall and I will report back if it fails.

> 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, d2911-2.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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