Regression profiling

[Andrus Adamchik <an...@objectstyle.org>]

I just setup a Maven/Jetty/Jmeter combo to do some simple regression  
profiling of the code (per CAY-524). I was able to get some data  
comparing 1.1.4, M12 and HEAD performance:

http://dev.objectstyle.org/~andrus/profile/

CAY-524 has some initial writeup on how to run the profiler. I'll put  
more docs on Wiki in the future.

Preliminary conclusions:

* 1.2 and 1.1 are comparable in performance. Some things became  
better, some became worse, but nothing sticks out as really bad.

* 1.2 uses a different JDBC strategy than 1.1 (Statement.execute()  
instead of Statement.executeUpdate() + executeQuery()), so the  
profiles look different on different databases, as this is driver  
dependent. An extreme case - HSQLD "file:" URLs (not shown above)  
result in 4x slowdown in 1.2, while after switching to "mem:" URL,  
the differences between releases become insignificant.

* Still we can probably do better, so I will continue working on  
profiling the individual scenarios (per CAY-525).

Also if anybody finds a scenario that behaves unusually slowly  
compared to 1.1 or in general (such as CAY-438), please report them  
via Jira.

Andrus