[jira] Commented: (DERBY-2911) Implement a buffer manager using java.util.concurrent classes

["Dyre Tjeldvoll (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12539551 ] 

Dyre Tjeldvoll commented on DERBY-2911:
---------------------------------------

Hi Knut, 

Your interpretation seems reasonable to me. Have you tried
lifting restriction a), so that the background cleaner is allowed
to clean more than one page? Is there a reason not to let the
background cleaner re-queue itself?

> 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: d2911-1.diff, d2911-1.stat, 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-entry-javadoc.diff, d2911-unused.diff, d2911-unused.stat, d2911perf.java, perftest6.pdf
>
>
> 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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