How could I debug JDV memory allocation properly

We hare having trouble with memory allocation on our JDV server (using Red Hat JBoss Data Virtualization - Version 6.3.0) for some reason memory gets allocated but never released.

For simple queries memory increases just a little, however when we make complex joins etc, we are seeing scenarios with 20GB+ allocated heap.

I wonder if there is any inspection tool for debugging what is consuming it in JDV.

Our main datasource is an Oracle DS, but we do have a MariaDB being used too.