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我們正在運行最新版本的Hibernate 4和MySQL。我們所有的Hibernate實體都有一個版本字段，註釋爲@版本，因爲我們在整個開發板上使用了樂觀鎖定。我們在應用程序中沒有使用Pessimistic Locking。我的理解是，使用悲觀鎖定時可能會出現LockTimeoutExceptions，但是，即使我們不使用此鎖定策略，我們也經常這樣做。使用樂觀鎖定時發生Hibernate/MySQL LockTimeoutException
在這種特殊場景中，我們有一個執行程序服務，其大小爲1的線程池。當用戶執行某些操作時，我們會爲其他用戶創建通知。我們將此通知創建委託給執行者服務。這些通知可能需要一些時間才能創建，所以我們這樣做，因此用戶不必坐下來等待通知創建完成。我們使用一個單一大小的線程池，以便我們沒有多次處理通知等等。我們想要的是讓這些操作順序排列並運行。每個線程啓動單個事務，創建所有必要的通知，並提交所述事務並關閉實體管理器。
我們得到的異常的堆棧跟蹤如下。任何想法爲什麼我們會在如上所述的場景中鎖定？我不明白。
Lock wait timeout exceeded; try restarting transaction
2015-10-08 01:27:52,195 ERROR [NotificationPublishingRunnable] : could not execute statement
javax.persistence.LockTimeoutException: could not execute statement
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.wrapLockException(AbstractEntityManagerImpl.java:1812)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1715)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1683)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1206)
at za.co.bsg.ems.server.DB.merge(171bcc9:315)
at za.co.bsg.ems.server.repositories.AbstractRepository.merge(171bcc9 ---------------:158)
at za.co.bsg.ems.server.services.notification.EmployeeNotificationCRUDServiceSupport.createEmployeeNotification(171bcc9 remotes/origin/11_9 ---------------:97)
at za.co.bsg.ems.server.services.notification.EmployeeNotificationCRUDServiceSupport.createEmployeeNotifications(171bcc9 remotes/origin/11_9 ---------------:75)
at za.co.bsg.ems.server.services.notification.EmployeeNotificationCreatorSupport.createEmployeeNotifications(171bcc9 remotes/origin/11_9 -----------:80)
at za.co.bsg.ems.server.notification.handler.NotificationHandlerManagerSupport.createNotificationsFromRequest(171bcc9 remotes/origin/11_9 ----------:233)
at za.co.bsg.ems.server.runnable.notification.NotificationPublishingRunnable.run(171bcc9 remotes/origin/11_9 -------:64)
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)
Caused by: org.hibernate.exception.LockTimeoutException: could not execute statement
at org.hibernate.dialect.MySQLDialect$1.convert(MySQLDialect.java:447)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:211)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3558)
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:98)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:492)
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:197)
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:181)
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:216)
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:324)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:288)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.jpa.event.internal.core.JpaMergeEventListener.saveWithGeneratedId(JpaMergeEventListener.java:73)
at org.hibernate.event.internal.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:271)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:251)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:189)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:85)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:876)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:858)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:863)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1196)
... 10 more
Caused by: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:996)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3887)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3823)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2435)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2582)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2530)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1907)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2141)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2077)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2062)
at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:105)
at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:105)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208
[@ brent777]你有沒有找到解決這個問題的方法？我們有完全相同的問題。 –
@AndrewKew不幸的不是。 – brent777