If you look at this WIKI page, there is a caveat about "sub-pooling" within the JBossManagedConnectionPool

http://wiki.jboss.org/wiki/ConfigJCACommon
"Unless the ResourceAdapter has <reauthentication-support> using multiple security identities will create subpools for each identity."

The way this works is that we hold a map of CRI->SubPool
(CRI == ConnectionRequestInfo).

If there is sparse coverage of the CRI parameter space, you can end up with lots of subpools which holds
references to each CRI (the same issue also applies to pooling by Subject).

The sub-pools will be empted by the IdleRemover, but the sub-pools themselves will be retained
which could consume a lot a memory or even cause an OutOfMemoryError depending on the use case.

Currently the only way to clear these subpools is manually flush() the pool which will remove all the sub-pools
and allow them to be re-created as required.