[
https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Knut Anders Hatlen updated DERBY-2911:
--------------------------------------
Attachment: d2911-7a.diff
The attached patch 7a replaces patch 7. It implements reuse of free entries
when the cache is smaller than its max size. What's changed is that the scan
for reusable entries is performed by rotateClock() instead of a separate
method. This means that we will also try to reuse free entries when the cache
is full and we know there is at least one free entry, even though we didn't
find a free or evictable entry after scanning 20% of the cache.
Derbyall and suites.All both ran cleanly with the new buffer manager enabled in
modules.properties.
> 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.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
