我用s2sh做购物网站，里面用到了版本控制version，save和delete没有问题，但update就显示出错。
我一运行就点update,所以不存在已有一个线程在。
我觉得是这个问题，不知对不对。

以下是错误代码：
org.springframework.orm.hibernate4.HibernateOptimisticLockingFailureException: Object of class [com.fangyun.entity.Product] with identifier [0]: optimistic locking failed; nested exception is org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.fangyun.entity.Product#0]

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.fangyun.entity.Product#0]