[ http://issues.apache.org/jira/browse/DERBY-2122?page=all ]
Knut Anders Hatlen updated DERBY-2122:
--------------------------------------
Attachment: derby-2122-v1.diff
derby-2122-v1.stat
The attached patch removes the compatibility matrix from ContainerLock and
instead maintains a bit mask containing the type ids of the compatible lock
types. Compatibility checking between two lock types could therefore be
performed by a bitwise and of the the bit mask and the type id.
Similar changes were made to RowLock to keep the two classes consistent.
I have run some experiments with this patch and the test client from DERBY-1961
(single-record selects with 16 concurrent clients on embedded Derby).
Experiment 1: 40 runs (20 with clean trunk, 20 with patch for ContainerLock
only) consisting of 30 seconds warm-up and 60 seconds counting transactions.
Result: Average throughput increased by 1.2% with the patch.
Experiment 2: Same as above, but counting transactions for 100 seconds instead
of 60 seconds. Result: Average throughput increased by 1.7% with the patch.
Experiment 3: Same as above, but with the full patch (that is, both
ContainerLock and RowLock changed). Result: Average throughput increased by
1.9% with the patch.
I don't have a fancy script that calculates how significant these numbers are
(can do it on request, since I really need to refresh my statistics skills),
but they at least give an indication that the patch has a small positive impact.
Reviews would be appreciated. Thanks.
> 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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