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Date: Tue, 28 Nov 2006 12:51:22 -0800 (PST)
From: "Knut Anders Hatlen (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-2122) Optimize
 ContainerLock.isCompatible()
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    [ http://issues.apache.org/jira/browse/DERBY-2122?page=comments#action_12454117 ] 
            
Knut Anders Hatlen commented on DERBY-2122:
-------------------------------------------

Thanks Mike, that's a good point. Perhaps it would be even better if we left the 2-d arrays and built the bit masks from them at initialization time.

> Optimize ContainerLock.isCompatible()
> -------------------------------------
>
>                 Key: DERBY-2122
>                 URL: http://issues.apache.org/jira/browse/DERBY-2122
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store, Performance
>    Affects Versions: 10.2.1.6
>            Reporter: Knut Anders Hatlen
>         Assigned To: Knut Anders Hatlen
>            Priority: Trivial
>         Attachments: derby-2122-v1.diff, derby-2122-v1.stat
>
>
> The numbers at http://wiki.apache.org/db-derby/Derby1961MethodCalls indicate that ContainerLock.isCompatible() is called many times per transaction, at least when there are multiple concurrent clients operating on the same containers. Currently, it looks into a two-dimensional array to find out whether two locks are compatible. This could be implemented more efficiently, for instance by having a bit pattern in each ContainerLock object representing which lock types it is compatible with.

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