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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2911) Implement a buffer manager using java.util.concurrent classes
Date Mon, 10 Mar 2008 14:03:46 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12576992#action_12576992
] 

Knut Anders Hatlen commented on DERBY-2911:
-------------------------------------------

I improved some comments in revision 635556 to address 1a and 1d.

1b and 1c were addressed in revision 635183 as part of DERBY-3493.

> 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-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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