I'm having the same issue... JTA managed transactions with a single statefull session that is accesed concurrently...
Because SingleSessionCommandService uses a single instance of JpaPersistenceContextManager that returns the same EntityManager s will result in inconsistent results when it's accesed concurrently. My workaround was to implement a thread safe ProcessPersistenceContextManager and set it in the drools Environment when creating the session. ( env.set(EnvironmentName.PERSISTENCE_CONTEXT_MANAGER, persistenceContextManager));.