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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 Thu, 27 Mar 2008 13:57:24 GMT

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

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

    Attachment: d2911-15.diff
                d2911-14.diff

Attaching two new patches for review:

d2911-14.diff - rewrites the part of ClockPolicy.shrinkMe() that Øystein mentioned in his
comment 4e. It is not supposed to change the behaviour, only make the relationship between
the variables pos and index clearer.

d2911-15.diff - removes the method ClockPolicy.trimeMe() since it's only adding complexity
and doesn't have any real value (I think).

Derbyall and suites.All ran cleanly (except ManagementMBeanTest which has failed for some
time in the nightly regression tests too).

> 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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