LAMS 2.3 uses JBoss 4.0.2 and Hibernate 3.2. Before deploying LAMS, this server does several steps. One of them is deployment of service(s) in "jboss-hibernate.deployer" directory. These services are needed for cache management, later also used in LAMS. To work they also need Hibernate 3. JBoss contains a distribution of Hibernate 3.0.5 which is placed in "jboss-hibernate.deployer". During start up of these services, some Hibernate 3.0.5 classes are loaded into memory, but *they are not unloaded* afterwards, as we use single ClassLoader for whole deployment.
This way we have LAMS using Hibernate 3.0.5, instead of 3.2 which is deployed along with the project. The situation can be even more complicated, as it is possible that some Hibernate classes come from 3.0.5 distribution and some from 3.2.

Even though this situation was transparent for LAMS developers, it has some impact on the project behaviour. Some Hibernate features are not available like they should be in version 3.2. It prevents proper debugging. This might also be the reason for LDEV-57.

After putting Hibernate 3.2 into JBoss shared library, thus making "jboss-hibernate.deployer" and LAMS finally use this version, multiple problems appeared (this also proves that LAMS was not using 3.2 as expected).
This JIRA contains changes leading to proper upgrade to Hibernate 3.3 (newest version), smooth project operation afterwards and any Hibernate-bound tuning that will increase efficiency of LAMS.