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https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12525012
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Knut Anders Hatlen commented on DERBY-2911:
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Thanks Manish, that's a great suggestion, but since the objects in the cache
need to implement the Cacheable interface and Cacheable.getIdentity() returns
an Object, we're kind of locked into declaring the hash key as Object. We could
work around that problem by casting the identity to the parametrized type K,
like
K key = (K) cacheable.getIdentity();
cache.remove(key);
but that'll give us a compile-time warning about an unchecked cast. So until
the interfaces that we need to work with are rewritten using generics, I think
it's best not to parametrize the key type.
> 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-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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