我正在使用Hibernate,试图模拟对数据库中同一行的两次并发更新。
编辑:我把em1.getTransaction().commit移动到em1.flush()后面;现在我没有收到StaleObjectException,这两个事务都成功提交了。
Session em1=Manager.sessionFactory.openSession();
Session em2=Manager.sessionFactory.openSession();
em1.getTransaction().begin();
em2.getTransaction().begin();
UserAccount c1 = (UserAccount)em1.get( UserAccount.class, "root" );
UserAccount c2 = (UserAccount)em2.get( UserAccount.class, "root" );
c1.setBalance( c1.getBalance() -1 );
em1.flush();
System.out.println("balance1 is "+c2.getBalance());
c2.setBalance( c2.getBalance() -1 );
em2.flush(); // fail
em1.getTransaction().commit();
em2.getTransaction().commit();
System.out.println("balance2 is "+c2.getBalance());
在em2.flush()
上我遇到了以下异常。为什么会出现这种情况?
2009-12-23 21:48:37,648 WARN JDBCExceptionReporter:100 - SQL Error: 1205, SQLState: 41000
2009-12-23 21:48:37,649 ERROR JDBCExceptionReporter:101 - Lock wait timeout exceeded; try restarting transaction
2009-12-23 21:48:37,650 ERROR AbstractFlushingEventListener:324 - Could not synchronize database state with session
org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
at org.hibernate.persister.entity.AbstractEntityPersister.processGeneratedProperties(AbstractEntityPersister.java:3702)
at org.hibernate.persister.entity.AbstractEntityPersister.processUpdateGeneratedProperties(AbstractEntityPersister.java:3691)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:147)
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:1028)
at com.ch.whoisserver.test.StressTest.main(StressTest.java:54)
Caused by: java.sql.BatchUpdateException: Lock wait timeout exceeded; try restarting transaction
at com.mysql.jdbc.PreparedStatement.executeBatchSerially(PreparedStatement.java:1213)
at com.mysql.jdbc.PreparedStatement.executeBatch(PreparedStatement.java:912)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
... 10 more