db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-2911) Implement a buffer manager using java.util.concurrent classes
Date Tue, 11 Dec 2007 13:57:43 GMT

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

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

    Attachment: d2911-10.stat
                d2911-10.diff

Attaching a new patch (d2911-10). This patch addresses the potential deadlock issue if user
code (i.e., Cacheable.setIdentity() or Cacheable.createIdentity()) reenters the cache. It
makes the callers of setIdentity()/createIdentity() release the ReentrantLock on the cache
entry before calling one of those methods. Other threads that want to access the object in
that entry therefore have to wait until the identity has been set, whereas threads scanning
the cache (e.g., checkpoint or clock rotation) skip the entry instead of waiting since they
just see an invalid/kept entry.

All the regression tests passed when I enabled ConcurrentCache 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: cleaner.diff, cleaner.tar, d2911-1.diff, d2911-1.stat, d2911-10.diff,
d2911-10.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, d2911-9.diff, d2911-9.stat, d2911-entry-javadoc.diff, d2911-unused.diff,
d2911-unused.stat, d2911perf.java, derby-2911-8.diff, derby-2911-8.stat, perftest6.pdf, poisson_patch8.tar
>
>
> 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.


Mime
View raw message