org.springframework.dao.CannotAcquireLockException 的解决》

        直接上 bug 的详细信息：

2012-03-12 15:20:31 XmlBeanDefinitionReader [INFO] Loading XML bean definitions from class path resource [org/springframework/jdbc/support/sql-error-codes.xml]2012-03-12 15:20:31 SQLErrorCodesFactory [INFO] SQLErrorCodes loaded: [DB2, Derby, H2, HSQL, Informix, MS-SQL, MySQL, Oracle, PostgreSQL, Sybase]2012-03-12 15:20:31 ExceptionUtil [ERROR] SqlMapClient operation; SQL [];   --- The error occurred in com/defonds/syncpath/dao/operation.xml.  --- The error occurred while applying a parameter map.  --- Check the operation.updateShareStatus-InlineParameterMap.  --- Check the statement (update failed).  --- Cause: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction; nested exception is com.ibatis.common.jdbc.exception.NestedSQLException:   --- The error occurred in com/defonds/syncpath/dao/operation.xml.  --- The error occurred while applying a parameter map.  --- Check the operation.updateShareStatus-InlineParameterMap.  --- Check the statement (update failed).  --- Cause: java.sql.SQLException: Lock wait timeout exceeded; try restarting transactionorg.springframework.dao.CannotAcquireLockException: SqlMapClient operation; SQL [];   --- The error occurred in com/defonds/syncpath/dao/operation.xml.  --- The error occurred while applying a parameter map.  --- Check the operation.updateShareStatus-InlineParameterMap.  --- Check the statement (update failed).  --- Cause: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction; nested exception is com.ibatis.common.jdbc.exception.NestedSQLException:   --- The error occurred in com/defonds/syncpath/dao/operation.xml.  --- The error occurred while applying a parameter map.  --- Check the operation.updateShareStatus-InlineParameterMap.  --- Check the statement (update failed).  --- Cause: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction	at org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator.doTranslate(SQLErrorCodeSQLExceptionTranslator.java:244)	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)	at org.springframework.orm.ibatis.SqlMapClientTemplate.execute(SqlMapClientTemplate.java:212)	at com.defonds.frameworkcommons.dao.BaseDaoImpl.execute(BaseDaoImpl.java:31)	at com.defonds.frameworkcommons.dao.BaseDaoImpl.update(BaseDaoImpl.java:97)	at com.defonds.syncpath.service.operation.impl.OperationServiceImpl.revokeSharedFolder(OperationServiceImpl.java:287)	at com.defonds.syncpath.service.share.impl.ShareServiceImpl.handleRevokeSharedFolder(ShareServiceImpl.java:312)	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 com.defonds.interfaceframework.controller.Action.invokeMethod(Action.java:256)	at com.defonds.interfaceframework.controller.Action.execute(Action.java:206)	at com.defonds.interfaceframework.controller.DispatcherServlet.service(DispatcherServlet.java:144)	at com.defonds.syncpath.common.ArcSyncDispatcherServlet.service(ArcSyncDispatcherServlet.java:51)	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)	at java.lang.Thread.run(Thread.java:619)

        分析原因：

        Spring 事务嵌套造成死锁。FileServiceImpl 里嵌入了 OperationService：

	private OperationService operationService;

        FileServiceImpl 的 delete 方法里对 MySQL 的 file 表有操作，而 OperationService 里的 revokeSharedFolder 方法也对同一张表有更新操作。事务嵌套，造成死锁。

        解决方案：

        当前调用事务的方法设置为 Propagation.SUPPORTS：

	@Transactional(propagation=Propagation.SUPPORTS)//by Defonds,for BUG094537	@Override	public void delete(int uid, int[] itemIds) {		if (itemIds != null && itemIds.length > 0) {

java.sql.SQLException: Lock wait timeout exceeded --转