Database connections not closed after idle-timeout in wildfly Datasource

Question

I have an application running under wildfly 8.1 The database connections used in the applications are taken from a Datasource defined in standalone.xml file.

Proble

Answer 1

It turns out that Hibernate was holding connection and not releasing them to the Pool. Irrespective of the fact that we are using thread local context. But after adding <property name="hibernate.connection.release_mode">after_transaction</property> to the hibernate config. The problem got solved.

PS: I still dont understand why we need to define this explicitly and why the auto release_mode would not release the connection once the session is closed.