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Date: Wed, 28 Feb 2007 04:46:57 -0800 (PST)
From: "Olav Sandstaa (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-2328) Reduce monitor contention in
 SinglePool
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    [ https://issues.apache.org/jira/browse/DERBY-2328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12476570 ] 

Olav Sandstaa commented on DERBY-2328:
--------------------------------------

Adding comments sent earlier today to derby-dev when JIRA was unavailable:
=====================================================

I have downloaded and reviewed the patch. I like the introduction of the CompatibilitySpace interface and having to explicitly to create compatibility spaces. It mades the code more readable. Also removing the hash table from SinglePool is good both for simplifying the code, readability and performance (CPU and monitor contention). The patch looks very good.

I have only some very minor nits:

* java/engine/org/apache/derby/impl/services/locks/LockSpace.java:

   -since you have changed the signature of the LockSpace constructor you should consider adding JavaDoc describing the new parameter (Object owner).
   -it might also be an idea to explain the "owner" concept in the JavaDoc for the class since this is a new concept you are introducing?
    (and if you change the JavaDoc for the class, you can probably also change the sentence refeering the "a hashtable keyed by..." to a "hash map keyed by....")

I have run the derbyall and Junit test suites with the patch. Only the two tests that currently fail in the thinderbox test failed.

+1 to commit this patch.

Thanks for the work on this, Knut Anders!

Regards,
Olav 

> Reduce monitor contention in SinglePool
> ---------------------------------------
>
>                 Key: DERBY-2328
>                 URL: https://issues.apache.org/jira/browse/DERBY-2328
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Performance, Services
>    Affects Versions: 10.3.0.0
>            Reporter: Knut Anders Hatlen
>         Assigned To: Knut Anders Hatlen
>            Priority: Minor
>         Attachments: derby-2328.diff, derby-2328.stat, unused.diff
>
>
> When multiple threads enter the lock manager, there might be contention on SinglePool's monitor. The contention should be reduced in order to improve scalability.

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