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Date: Thu, 20 Sep 2007 01:05:31 -0700 (PDT)
From: "Knut Anders Hatlen (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-2911) Implement a buffer manager using
 java.util.concurrent classes
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    [ https://issues.apache.org/jira/browse/DERBY-2911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12529019 ] 

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

I manually enabled the new buffer manager in modules.properties and ran suites.All + derbyall. The number of test cases failing in suites.All is now 7, of which 6 are expected failures in StatementPlanCacheTest mentioned in a previous comment. The last JUnit failure is in ImportExportTest:client:

1) ImportExportTest:clientjava.sql.SQLException: Limitation: Record cannot be updated or inserted due to lack of space on the page. Use the parameters derby.storage.pageSize and/or derby.storage.pageReservedSpace to work around this limitation.

In derbyall, 8 tests failed:

derbyall/derbyall.fail:unit/cacheService.unit
derbyall/storeall/storeall.fail:store/rollForwardRecovery.sql
derbyall/storeall/storeall.fail:store/backupRestore1.java
derbyall/storeall/storeall.fail:store/OnlineBackupTest1.java
derbyall/storeall/storeall.fail:unit/T_RawStoreFactory.unit
derbyall/storeall/storeall.fail:unit/T_b2i.unit
derbyall/storeall/storeall.fail:unit/recoveryTest.unit
derbyall/storeall/storeall.fail:store/RecoveryAfterBackup.java

All the failures in derbyall seem to happen because entries are left in the cache in an invalid state if Cacheable.setIdentity() or Cacheable.createIdentity() throws a StandardException. I will fix this by removing the entries whose identity cannot be set/created.

> 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-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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