行被另一个事务更新或删除（或未保存的值映射不正确）

Posted 2021-03-27

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我有一个在Web服务器上运行的java项目。我总是遇到这个例外。

我阅读了一些文档，发现悲观锁定（或乐观，但我认为悲观更好）是防止此异常的最佳方法。

但我找不到任何解释如何使用它的明确例子。

我的方法是这样的：

@Transactional
Public void test(Email email, String Subject){
   getEmailById(String id);
   email.setSubject(Subject);
   updateEmail(email);
}

而：

Email是一个hibernate类（它将是数据库中的一个表）
getEmailById(String id)是一个返回email的函数（此方法未使用@Transctional注释）
updateEmail(email)：是一种更新电子邮件的方法。

注意：我使用hibernate进行保存，更新等等（例如：qazxsw poi）

例外：

session.getcurrentSession.save(email)

答案

通常不建议使用悲观锁定，并且在数据库方面的性能方面非常昂贵。您提到的问题（代码部分）有些事情并不清楚，例如：

如果您的代码同时被多个线程访问。
你是如何创建ERROR 2011-12-21 15:29:24,910 Could not synchronize database state with session [myScheduler-1] org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [email#21] at org.hibernate.persister.entity.AbstractEntityPersister.check(AbstractEntityPersister.java:1792) at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2435) at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:2335) at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2635) at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:115) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:168) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1027) at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:365) at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137) at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:656) at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:754) at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:723) at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:393) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:120) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) at $Proxy130.generateEmail(Unknown Source) at com.admtel.appserver.tasks.EmailSender.run(EmailNotificationSender.java:33) at com.admtel.appserver.tasks.EmailSender$$FastClassByCGLIB$$ea0d4fc2.invoke(<generated>) at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149) at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161) at org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor.invoke(AfterReturningAdviceInterceptor.java:50) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161) at org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:50) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621) at com.admtel.appserver.tasks.EmailNotificationSender$$EnhancerByCGLIB$$33eb7303.run(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.util.MethodInvoker.invoke(MethodInvoker.java:273) at org.springframework.scheduling.support.MethodInvokingRunnable.run(MethodInvokingRunnable.java:65) at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:51) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441) at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:180) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:204) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:680) ERROR 2011-12-21 15:29:24,915 [ exception thrown < EmailNotificationSender.run() > exception message Object of class [Email] with identifier [211]: optimistic locking failed; nested exception is org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [Email#21] with params ] [myScheduler-1] org.springframework.orm.hibernate3.HibernateOptimisticLockingFailureException: Object of class [Email] with identifier [21]: optimistic locking failed; nested exception is对象的（不确定你是否使用Spring）？

Hibernate session。因此，如果有多个线程访问同一个会话并尝试更新同一个数据库实体，那么您的代码可能最终会出现这样的错误情况。

所以这里发生的是多个线程尝试更新同一个实体，一个线程成功，当下一个线程提交数据时，它看到它已被修改并最终抛出Session objects are NOT thread-safe。

编辑：

有一种方法可以在Hibernate中使用悲观锁定。看看StaleObjectStateException。但这种机制似乎存在一些问题。然而，我遇到了在hibernate（this link）中发布的错误。 bug中提到的场景如下：