登录事件监听器出错？

Question

我正在使用Spring Security进行身份验证。我正在使用登录事件监听器来记录用户的上次登录时间

在conf / spring / resources.groovy我有

loginEventListener(LoginEventListener)

并将侦听器定义为

class LoginEventListener implements
    ApplicationListener<InteractiveAuthenticationSuccessEvent> {

    //deal with successful login
    void onApplicationEvent(InteractiveAuthenticationSuccessEvent event) {
        User.withTransaction {

            def user = User.findById(event.authentication.principal.id)
            if(!user.isAttached())
                user.attach()
            user.lastLoginTime = new Date() // update login time
            user.save(flush: true, failOnError: true)


        }


    }


}

我现在得到的错误是

user.save(flush: true, failOnError: true)

错误如下

ERROR 2017-05-31 16:04:15,715 [ajp-bio-8109-exec-9659] events.PatchedDefaultFlushEventListener: Could not synchronize database state with session
org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [User#7]
    at LoginEventListener$_onApplicationEvent_closure1.doCall(LoginEventListener.groovy:18)
    at org.grails.datastore.gorm.GormStaticApi.withTransaction(GormStaticApi.groovy:686)
    at LoginEventListener.onApplicationEvent(LoginEventListener.groovy:12)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

我想了解这个错误的原因，我该如何避免呢？是flush：true是错误的原因吗？我感谢任何帮助！谢谢！