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https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-2911:
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Attachment: d2911-4.diff
Attaching a patch (d2911-4.diff) which makes a couple of small changes to
ConcurrentCache.java:
1) Make findFreeCacheable() take the CacheEntry as a parameter call
setCacheable() on the entry instead of returning a Cacheable. When the
replacement algorithm is implemented, findFreeCacheable() is going to need the
CacheEntry reference in order to insert the entry into the replacement policy's
internal data structure (e.g., clock).
2) Make removeEntry() take a key (object identity) instead of a CacheEntry so
that it also can be used to remove entries from the cache when
setIdentity/createIdentity failed.
> 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-entry-javadoc.diff, d2911-unused.diff, d2911-unused.stat, d2911perf.java
>
>
> 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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