David Van Couvering wrote:
Yes, this was my experience also. You can't have multiple
configurations in a VM instance, because everything is dependent on
system properties (both Derby itself as well as the test harness
infrastructure). I don't *think* using classloaders will help because
system properties, as I understand it, are VM-wide and span
classloaders. But I haven't explicitly tested that.
David
Yes, system properties are VM-wide, but they can be changed at any time.
The problem is if the properties are read and used only once, when the
driver is loaded, since it is impossible to instruct a class loader to
"unload" anything.
It is possible to load the driver multiple times with different class
loaders. However, this requires that the driver is not in the classpath
for the VM, otherwise your class loaders will delegate to the system
classloader, which finds the driver and caches it. Thus, each class
loader will return the same class, which has been initialized only once.
If it is impossible to exclude the driver from the VM's classpath (due
to the test harness), it is still possible to load the driver multiple
times (with different system property settings) using a bit of a hack:
Make your own ClassLoader which doesn't delegate to its parent
classloader for certain class names (the driver's classes).
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�yvind Bakksj�
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