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Posted to derby-dev@db.apache.org by "Knut Anders Hatlen (JIRA)" <ji...@apache.org> on 2007/09/03 12:07:19 UTC

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

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

Knut Anders Hatlen updated DERBY-2911:
--------------------------------------

    Attachment: d2911perf.java

I have written a small test which can be used to measure performance improvements in this issue. It is a multi-threaded test which performs primary-key lookups. Each thread has its own table to work on to avoid contention on latches (which is a scalability issue separate from the one we're trying to solve in this JIRA issue).

It's a standalone Java program for now since our JUnit framework doesn't support multi-threaded tests yet, as far as I can see. To run the test, use this command line:

  java d2911perf <DB-URL> <THREADS> <WARMUP> <COLLECT>

The test will have a warm-up phase of <WARMUP> seconds and collect results for <COLLECT> seconds.

> 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-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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