We are moving rather big project from jBoss 2.2 to 2.4
using mySQL via mm.mysql-2.0.7-bin.jar in both cases.

All junit tests of our project run fine at 2.2 but fail at 2.4

The reasons looks similar but not the same: from 'jdbc not bound' at the middle of test to infinite recursion finished by exception with appropriate (thousands of lines) stack.

We found the reason:
connect to jdbc was done independently of dirty flag. But disconnect was done accuratly each time!
I.E. the only reason of errors was a high load of jdbc connections pool.

Well, this was fixed but: first, it wasn't a bug, just ineffective peace of code and second, what will we have when not just a test but real work will load jBoss hardly?

Does jdbc pool in jBoss 2.4.4 have perfomance problems or what else may have happened with our tests?