In my code, i have a servlet , 2 stateless session beans: in the servlet, i use jndi to find a stateless bean (A) and invoke a method methodA in A: -------- (Stateless bean A): @EJB StatelessBeanB beanB; methodA(obj) { beanB.save(obj); } ------- (Stateless bean B, where container inject a persistence context): @PersistenceContext private EntityManager em; save(obj) { em.persist(obj); } ---------- it is said entity manager is not thread safe, so it should not be an instance variable. But in the code above, the variable "em" is an instance variable of stateless bean B, Does it make sense to put it there using pc annotation? is it then thread safe when it is injected (manager) by container? since i think B is a stateless session bean, so easy request will share the instance variable of B class which is not a thread safe way. So , could you please give me any guide on this problem? make me clear. any is appreciated. thank you:)