hibernate不知道怎么删除？

Hibernate  的缓存没有清理.
代码改一下.
  try {
            Session session = getSession();
            session.delete(persistentInstance);
            session.beginTrasaction().commit();
            log.debug("delete successful");
        } catch (RuntimeException re) {
            log.error("delete failed", re);
            throw re;
        }