mysql死锁异常分析及解决

前言

其实在这次之前也发生过死锁异常，但当时并没当回事，也没分析数据，简单的认为是偶发现象，并且是修改同一用户产生，于是就在最初添加了select for update，直到这两天发生了好几笔，分析数据发现并不是之前猜测的那样

问题产生

这两天老接到运维通知，说某客户又发生了卡单现象，让我分析下问题，然后找来日志，异常信息如下：

### Error updating database.  Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
### The error may involve io.renren.modules.others.dao.PlayerDao.saveZhsz-Inline
### The error occurred while setting parameters
### SQL: INSERT INTO shpt_zhgl_zhsz(rq, jysr, ztzhye, zhye, shid) select ?, ?, zhye, zhye + ?, user_id from sys_user where user_id = ? ON DUPLICATE KEY UPDATE jysr = jysr + values(jysr), zhye = values(zhye)
### Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
; Deadlock found when trying to get lock; try restarting transaction; nested exception is com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction

org.springframework.dao.DeadlockLoserDataAccessException: 
### Error updating database.  Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
### The error may involve io.renren.modules.others.dao.PlayerDao.saveZhsz-Inline
### The error occurred while setting parameters
### SQL: INSERT INTO shpt_zhgl_zhsz(rq, jysr, ztzhye, zhye, shid) select ?, ?, zhye, zhye + ?, user_id from sys_user where user_id = ? ON DUPLICATE KEY UPDATE jysr = jysr + values(jysr), zhye = values(zhye)
### Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
; Deadlock found when trying to get lock; try restarting transaction; nested exception is com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
	at org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator.doTranslate(SQLErrorCodeSQLExceptionTranslator.java:267)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy84.update(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:294)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
	at com.sun.proxy.$Proxy115.saveZhsz(Unknown Source)
	at io.renren.modules.others.service.PlayerService.updateOrder(PlayerService.java:195)
	at io.renren.modules.others.service.PlayerService$$FastClassBySpringCGLIB$$cd68b7fd.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689)
	at io.renren.modules.others.service.PlayerService$$EnhancerBySpringCGLIB$$5688f237.updateOrder(<generated>)
	at io.renren.modules.others.service.PlayerService$$FastClassBySpringCGLIB$$cd68b7fd.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689)
	at io.renren.modules.others.service.PlayerService$$EnhancerBySpringCGLIB$$2c59a973.updateOrder(<generated>)
	at io.renren.modules.others.controller.PlayerController.a(PlayerController.java:967)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:112)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at io.renren.common.xss.XssFilter.doFilter(XssFilter.java:23)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61)
	at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
	at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
	at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
	at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
	at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
	at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:387)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at io.renren.config.LicenseFilter.doFilter(LicenseFilter.java:136)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at io.renren.config.FilterConfig$1.doFilterInternal(FilterConfig.java:82)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1598)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:123)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
	at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:955)
	at com.mysql.cj.jdbc.ClientPreparedStatement.execute(ClientPreparedStatement.java:372)
	at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:497)
	at sun.reflect.GeneratedMethodAccessor53.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59)
	at com.sun.proxy.$Proxy119.execute(Unknown Source)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)
	at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)
	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
	at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
	... 108 common frames omitted

异常复现

分析日志发现，出现的几次都是在并发时发生，并且商户都有上级代理，本地并发测试，成功复现

原因分析

数据库相关锁的概念在此不赘述，具体请自行度娘

数据库运行命令：

show engine innodb status

得到日志，主要分析如下片段，是最后一次死锁信息:

------------------------
LATEST DETECTED DEADLOCK
------------------------
# 这里显示了最近一次发生死锁的日期和时间
2021-03-16 09:56:00 0x3444
*** (1) TRANSACTION:
# 这行表示事务5245990，ACTIVE 0 sec表示事务处于活跃状态0s，inserting表示正在执行插入操作
# 常见的其他状态:
#	starting index read 			表示正在使用索引读取数据行。
# 	fetching rows 					表示事务状态在row_search_for_mysql中被设置，表示正在查找记录。
#	updating or deleting 			表示事务已经真正进入了Update/delete的函数逻辑（row_update_for_mysql）
#	thread declared inside InnoDB 	说明事务已经进入innodb层。通常而言 不在innodb层的事务大部分是会被回滚的。
TRANSACTION 5245990, ACTIVE 0 sec inserting
# 这行表示正在使用2个表，且涉及锁的表有2个
mysql tables in use 2, locked 2
# 这行表示在等待5把锁，占用内存1136字节，涉及2行记录
# 如果事务已经锁定了几行数据，这里将会有一行信息显示出锁定结构的数目（注意，这跟行锁是两回事）和堆大小，堆的大小指的是为了持有这些行锁而占用的内存大小
LOCK WAIT 5 lock struct(s), heap size 1136, 2 row lock(s)
# 这行表示该事务的线程ID信息，操作系统句柄信息，连接来源、用户
MySQL thread id 4949, OS thread handle 14000, query id 980983 180.126.46.39 root Sending data
# 这行表示事务涉及的SQL
INSERT INTO shpt_zhgl_zhsz(rq, jysr, ztzhye, zhye, shid) select '2021-03-13', 8.03, zhye, zhye + 8.03, user_id from sys_user where user_id = 32 ON DUPLICATE KEY UPDATE jysr = jysr + values(jysr), zhye = values(zhye)
# 这行信息表示第一个事务正在等待锁被授予
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
# 这行信息表示等待的锁是一个record lock，空间id是233，页编号为3，大概位置在页的168位处，锁发生在表`zfpt`.`shpt_zhgl_zhsz`的主键上，是一个X锁，insert intention waiting表示正在等待插入意向锁。 
# 几种锁的类型：
#	S锁(shared)：共享锁，多个读操作对同一个资源共享同一个锁，多个读操作可以同时进行而不会互相影响。因为读操作并不会改变数据内容，所以多个事务可以共享同一个锁，并行地读取同一个资源，这样可以提高并发效率。
#	X锁(exclude)：排他锁，当两个事务同时对表中某行数据进行更新操作时，若一个事务先到达并给该行加上排它锁，那么另一个事务就不能在该行加任意类型的锁，直到第一个事务释放了该行的锁。因此，排它锁可以确保在同一时间只有一个事务可以对被加锁的资源进行修改操作，从而避免出现数据竞争和不一致问题。
#	I锁(Intent Lock)：意向锁，数据库中的一种表级锁，在行级锁的基础上引入的一种概念。意向锁是用于解决多粒度锁定而设计的，可以避免行级锁和表级锁之间的冲突。
#		IS锁(Intention Shared Lock)：意向共享锁，在一个事务需要对表中某些行加共享锁（S锁）时，事务首先需要获得表的意向共享锁（IS锁）
#		IX锁(Intention Exclusive Lock)：意向排他锁，指的是在一个事务需要对表中某些行加排它锁（X锁）时，事务首先需要获得表的意向排它锁（IX锁）
# 意向锁简单来说就是添加行锁时，给表添加一个标识表明该表已经存在共享锁或者是排它锁，其他事务需要加锁直接读取该标识判断是否已经存在锁。
#	Gap-Lock：间隙锁，间隙锁就是两个值之间的空隙加锁，是Innodb在可重复读隔离级别下为了解决幻读问题而引入的一种锁机制。需注意间隙锁只会在可重复读隔离级别（REPEATABLE-READ）下才会生效。
#	Next-key Locks：临键锁，临键锁（Next-key Locks）是MySQL InnoDB存储引擎实现的一种数据行级别的锁机制，它是行级锁与间隙锁的组合，即位于索引记录与索引区间之间的一种排它锁。
# 临键锁主要目的是为了解决幻读问题，能够封锁该条记录相邻两个键之间的空白区域，防止其他事务在这个区域内插入、修改、删除数据。临键锁只与非唯一索引列有关，在唯一索引列（包括主键列）上不存在临键锁
RECORD LOCKS space id 233 page no 3 n bits 168 index PRIMARY of table `zfpt`.`shpt_zhgl_zhsz` trx id 5245990 lock_mode X insert intention waiting
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0
 0: len 8; hex 73757072656d756d; asc supremum;;

*** (2) TRANSACTION:
TRANSACTION 5245989, ACTIVE 0 sec setting auto-inc lock
mysql tables in use 2, locked 2
9 lock struct(s), heap size 1136, 6 row lock(s), undo log entries 2
MySQL thread id 4950, OS thread handle 13380, query id 980987 180.126.46.39 root Sending data
INSERT INTO shpt_zhgl_zhsz(rq, dlsr, ztzhye, zhye, shid) select '2021-03-13', 1.00, zhye, zhye + 1.00, user_id from sys_user where user_id = 1 ON DUPLICATE KEY UPDATE dlsr = dlsr + values(dlsr), zhye = values(zhye)
# 下面这部分是事务二的持有锁信息：
*** (2) HOLDS THE LOCK(S):
#从这两行持有锁信息上看，就是事务1正在等待的锁。
RECORD LOCKS space id 233 page no 3 n bits 168 index PRIMARY of table `zfpt`.`shpt_zhgl_zhsz` trx id 5245989 lock_mode X
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0
 0: len 8; hex 73757072656d756d; asc supremum;;

# 下面这部分是事务二正在等待的锁
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
TABLE LOCK table `zfpt`.`shpt_zhgl_zhsz` trx id 5245989 lock mode AUTO-INC waiting
*** WE ROLL BACK TRANSACTION (1)

原来是并发时在业务中INSERT INTO shpt_zhgl_zhsz ON DUPLICATE KEY UPDATE这个商户时，有其他商户也在运行INSERT INTO shpt_zhgl_zhsz ON DUPLICATE KEY UPDATE，而又由于商户拥有上级代理，也会NSERT INTO shpt_zhgl_zhsz ON DUPLICATE KEY UPDATE上级代理的数据，从而产生了死锁

解决方案

1、mysql默认级别repeatable read导致的死锁问题，所以根据业务，决定修改隔离级别为
read committed，从而解决死锁问题

@Transactional(isolation = Isolation.READ_COMMITTED)
public int updateOrder(BigDecimal je, String status, String orderNo, String zfsj) {
	// xxxxx相关业务
}

2、可以在死锁业务外面添加循环，捕获死锁异常，发生死锁异常时循环执行，正常执行时结束循环

3、添加全局异常捕获器，在捕获器中获取本次请求的方法类型(GET/POST…)，方法路径，方法参数，contentType等等，重新请求一次

@ControllerAdvice
public class GlobalExceptionHandler {
	private Logger logger = LoggerFactory.getLogger(getClass());

	// 这是异常锁表，lock wait timeout导致业务失败时的处理，也是比较常见的问题
	@ResponseBody
	@ExceptionHandler(CannotAcquireLockException.class)
	public String cannotAcquireLockException(CannotAcquireLockException e) {
		DruidDataSource dds = SpringContextUtils.getBean("firstDataSource", DruidDataSource.class);
		try (DruidPooledConnection conn = dds.getConnection();
				Statement stmt = conn.createStatement();
				ResultSet rs = stmt.executeQuery("select trx_mysql_thread_id from INFORMATION_SCHEMA.INNODB_TRX"
						+ " where trx_state = 'RUNNING' and trx_started < adddate(now(), INTERVAL -60 SECOND)");
				PreparedStatement ps = conn.prepareStatement("kill ?")) {
			while (rs.next()) {
				ps.setLong(1, rs.getLong(1));
				ps.addBatch();
			}
			ps.executeBatch();
		} catch (SQLException ex) {
			logger.error(ex.getMessage(), ex);
		}
		logger.error(e.getMessage(), e);
		return "{\"code\": 500, \"msg\": \"acquire lock failure, already kill the lock thread, try again\"}";
	}

	// 笔者没有实现这种方式，只是返回了对应异常信息
	@ResponseBody
	@ExceptionHandler(DeadlockLoserDataAccessException.class)
	public String deadLockException(DeadlockLoserDataAccessException e) {
		logger.error(e.getMessage(), e);
		return "{\"code\": 500, \"msg\": \"deadlock found when trying to get lock, try again\"}";
	}
}