场景
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删除车辆信息同时异步通知查询服务更新
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查询服务采用 insert into view 方式增加数据（导致行级锁）
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查询服务和删除车辆 争夺车辆表的锁，造成死锁
服务报错日志
2022-11-18 14:56:17.133 DEBUG 8 --- [nio-6004-exec-7] s.j.s.SQLErrorCodeSQLExceptionTranslator : Translating SQLException with SQL state '40001', error code '1213', message [Deadlock found when trying to get lock; try restarting transaction] for task [### Error updating database. Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction### The error may exist in com/redstarcloud/sc/info/car/biz/mapper/InfoCarMapper.java (best guess)### The error may involve com.redstarcloud.sc.info.car.biz.mapper.InfoCarMapper.updateById-Inline### The error occurred while setting parameters### SQL: UPDATE info_car SET del_flag = ? WHERE id = ?### Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction]Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2c6f7da]Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2c6f7da]2022-11-18 14:56:17.134 DEBUG 8 --- [nio-6004-exec-7] o.s.j.d.DataSourceTransactionManager : Initiating transaction rollback2022-11-18 14:56:17.134 DEBUG 8 --- [nio-6004-exec-7] o.s.j.d.DataSourceTransactionManager : Rolling back JDBC transaction on Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@3a5a10c]2022-11-18 14:56:17.135 DEBUG 8 --- [nio-6004-exec-7] o.s.j.d.DataSourceTransactionManager : Releasing JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@3a5a10c] after transaction2022-11-18 14:56:17.136 DEBUG 8 --- [nio-6004-exec-7] .m.m.a.ExceptionHandlerExceptionResolver : Using @ExceptionHandler com.redstarcloud.sc.info.car.biz.handler.GlobalExceptionHandler#handleException(Exception)2022-11-18 14:56:17.138 ERROR 8 --- [nio-6004-exec-7] c.r.s.i.c.b.h.GlobalExceptionHandler : GlobalExceptionHandler system exceptionorg.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 exist in com/redstarcloud/sc/info/car/biz/mapper/InfoCarMapper.java (best guess)### The error may involve com.redstarcloud.sc.info.car.biz.mapper.InfoCarMapper.updateById-Inline### The error occurred while setting parameters### SQL: UPDATE info_car SET del_flag = ? WHERE id = ?### 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:271) at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:70) at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:88) at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:440) at com.sun.proxy.$Proxy211.update(Unknown Source) at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:287) at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.execute(MybatisMapperMethod.java:65) at com.baomidou.mybatisplus.core.override.MybatisMapperProxy$PlainMethodInvoker.invoke(MybatisMapperProxy.java:148) at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) at com.sun.proxy.$Proxy217.updateById(Unknown Source) at com.redstarcloud.sc.info.car.biz.service.impl.InfoCarServiceImpl.deleteInfoCarById(InfoCarServiceImpl.java:351) at com.redstarcloud.sc.info.car.biz.service.impl.InfoCarServiceImpl$$FastClassBySpringCGLIB$$7ed26d7e.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:779) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) at com.redstarcloud.sc.info.car.biz.service.impl.InfoCarServiceImpl$$EnhancerBySpringCGLIB$$c3af8a71.deleteInfoCarById(<generated>) at com.redstarcloud.sc.info.car.biz.controller.InfoCarController.deleteCarById(InfoCarController.java:99) at com.redstarcloud.sc.info.car.biz.controller.InfoCarController$$FastClassBySpringCGLIB$$f4538816.invoke(<generated>)......省略......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.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953) at com.mysql.cj.jdbc.ClientPreparedStatement.execute(ClientPreparedStatement.java:370) at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3461) at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_execute(FilterEventAdapter.java:440) at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3459) at com.alibaba.druid.proxy.jdbc.PreparedStatementProxyImpl.execute(PreparedStatementProxyImpl.java:167) at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:497) at sun.reflect.GeneratedMethodAccessor265.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.$Proxy358.execute(Unknown Source) at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:47) at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74) at sun.reflect.GeneratedMethodAccessor873.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:63) at com.sun.proxy.$Proxy356.update(Unknown Source) at sun.reflect.GeneratedMethodAccessor873.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:63) at com.sun.proxy.$Proxy356.update(Unknown Source) at com.baomidou.mybatisplus.core.executor.MybatisSimpleExecutor.doUpdate(MybatisSimpleExecutor.java:56) at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117) at com.baomidou.mybatisplus.core.executor.MybatisCachingExecutor.update(MybatisCachingExecutor.java:85) at sun.reflect.GeneratedMethodAccessor920.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49) at com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor.intercept(MybatisPlusInterceptor.java:106) at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61) at com.sun.proxy.$Proxy355.update(Unknown Source) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:197) at sun.reflect.GeneratedMethodAccessor1038.invoke(Unknown Source) 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:426) ... 122 common frames omitted2022-11-18 14:56:17.140 DEBUG 8 --- [nio-6004-exec-7] m.m.a.RequestResponseBodyMethodProcessor : Using 'application/json', given [application/json, text/plain, */*] and supported [application/json, application/*+json, application/json, application/*+json]2022-11-18 14:56:17.141 DEBUG 8 --- [nio-6004-exec-7] m.m.a.RequestResponseBodyMethodProcessor : Writing [R(code=1, msg=系统异常, data=null)]2022-11-18 14:56:17.141 DEBUG 8 --- [nio-6004-exec-7] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [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 exist in com/redstarcloud/sc/info/car/biz/mapper/InfoCarMapper.java (best guess)### The error may involve com.redstarcloud.sc.info.car.biz.mapper.InfoCarMapper.updateById-Inline### The error occurred while setting parameters### SQL: UPDATE info_car SET del_flag = ? WHERE id = ?### 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]2022-11-18 14:56:17.142 DEBUG 8 --- [nio-6004-exec-7] o.s.web.servlet.DispatcherServlet : Completed 200 OK2022-11-18 14:56:17.142 DEBUG 8 --- [nio-6004-exec-7] s.s.w.c.SecurityContextPersistenceFilter : Cleared SecurityContextHolder to complete request2022-11-18 14:56:18.514 DEBUG 8 --- [isson-netty-2-6] org.redisson.connection.DNSMonitor : Request sent to resolve ip address for master host: 10.0.10.122022-11-18 14:56:18.517 DEBUG 8 --- [sson-netty-2-20] org.redisson.connection.DNSMonitor : Resolved ip: /10.0.10.12 for master host: 10.0.10.12关键日志
### SQL: UPDATE info_car SET del_flag = ? WHERE id = ?### Cause: com.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction 从这两行可以得知，该错误是数据库的错误，是死锁错误异常而导致的回滚，关键 SQL（车辆软删除） 是：UPDATE info_car SET del_flag = ? WHERE id = ?
2.核心错误的调用方法是哪个，即事务开始的方法是哪个?
com.redstarcloud.sc.info.car.biz.service.impl.InfoCarServiceImpl.deleteInfoCarById(InfoCarServiceImpl.java:351)数据库死锁日志
对应数据库执行，数据库死锁日志
SHOW ENGINE INNODB STATUS;=====================================2022-11-18 14:04:51 140530272577280 INNODB MONITOR OUTPUT=====================================Per second averages calculated from the last 58 seconds-----------------BACKGROUND THREAD-----------------srv_master_thread loops: 268422 srv_active, 0 srv_shutdown, 669542 srv_idlesrv_master_thread log flush and writes: 0----------SEMAPHORES----------OS WAIT ARRAY INFO: reservation count 141626OS WAIT ARRAY INFO: signal count 2846865RW-shared spins 0, rounds 0, OS waits 0RW-excl spins 0, rounds 0, OS waits 0RW-sx spins 0, rounds 0, OS waits 0Spin rounds per wait: 0.00 RW-shared, 0.00 RW-excl, 0.00 RW-sx------------------------LATEST DETECTED DEADLOCK------------------------2022-11-18 13:46:45 140531872175872*** (1) TRANSACTION:TRANSACTION 19529038, ACTIVE 0 sec fetching rowsmysql tables in use 15, locked 15LOCK WAIT 44 lock struct(s), heap size 3488, 862 row lock(s), undo log entries 1MySQL thread id 102080, OS thread handle 140528418883328, query id 14694528 10.244.0.216 root executinginsert into _multi_info select * from v_multi_info where id='Vehic9'*** (1) HOLDS THE LOCK(S):RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529038 lock mode SRecord lock, heap no 2 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000001; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571031; asc W 1;; 3: len 9; hex e6b2aa313233343536; asc 123456;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 9; hex e6af94e4ba9ae8bfaa; asc ;; 9: len 6; hex e7baa2e889b2; asc ;; 10: SQL NULL; 11: len 1; hex 30; asc 0;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ac7ae900; asc z ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303031; asc CO00000001;; 17: SQL NULL; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000002; asc ;; 24: SQL NULL; 25: SQL NULL; 26: len 5; hex 99a5fa0000; asc ;; 27: len 5; hex 99b63b7efb; asc ;~ ;; 28: len 5; hex 6170705f63; asc app_c;; 29: len 30; hex 687474703a2f2f34372e3130332e3133382e38363a31383133392f736d61; asc http://47.103.138.86:18139/sma; (total 85 bytes); 30: len 4; hex 80000000; asc ;;Record lock, heap no 3 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000002; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571062; asc W b;; 3: len 10; hex e9999541313238373137; asc A128717;; 4: len 8; hex 8000000000000008; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 0; hex ; asc ;; 9: len 0; hex ; asc ;; 10: len 0; hex ; asc ;; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000005; asc ;; 13: len 5; hex 99ac7f08ae; asc ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: SQL NULL; 21: SQL NULL; 22: SQL NULL; 23: SQL NULL; 24: SQL NULL; 25: len 0; hex ; asc ;; 26: SQL NULL; 27: SQL NULL; 28: len 2; hex 5043; asc PC;; 29: len 0; hex ; asc ;; 30: len 4; hex 80000000; asc ;;Record lock, heap no 4 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000003; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571093; asc W ;; 3: len 10; hex e9999541313233343536; asc A123456;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: SQL NULL; 9: SQL NULL; 10: SQL NULL; 11: len 1; hex 30; asc 0;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ac8ef448; asc H;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303032; asc CO00000002;; 17: SQL NULL; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000004; asc ;; 24: SQL NULL; 25: SQL NULL; 26: SQL NULL; 27: SQL NULL; 28: len 5; hex 6170705f63; asc app_c;; 29: SQL NULL; 30: len 4; hex 80000000; asc ;;Record lock, heap no 5 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000004; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 010000015710c4; asc W ;; 3: len 9; hex e99995554651393930; asc UFQ990;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: SQL NULL; 9: SQL NULL; 10: SQL NULL; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ac9108bb; asc ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000007; asc ;; 24: SQL NULL; 25: SQL NULL; 26: SQL NULL; 27: SQL NULL; 28: len 5; hex 6170705f63; asc app_c;; 29: len 30; hex 687474703a2f2f34372e3130332e3133382e38363a31383133392f736d61; asc http://47.103.138.86:18139/sma; (total 85 bytes); 30: len 4; hex 80000000; asc ;;Record lock, heap no 6 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000005; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 010000015710f5; asc W ;; 3: len 9; hex e99995553838333838; asc U88388;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e59381e7898c; asc ;; 9: len 6; hex e799bde889b2; asc ;; 10: SQL NULL; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ac910b44; asc D;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000007; asc ;; 24: SQL NULL; 25: len 6; hex e8bda6e4bd8d; asc ;; 26: len 5; hex 99ac900000; asc ;; 27: len 5; hex 99acbc0000; asc ;; 28: len 2; hex 7063; asc pc;; 29: SQL NULL; 30: len 4; hex 80000000; asc ;;Record lock, heap no 7 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000006; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571126; asc W &;; 3: len 9; hex e99995553730363338; asc U70638;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5ae9de9a9ac; asc ;; 9: len 6; hex e799bde889b2; asc ;; 10: len 12; hex e5a487e6b3a8e4bfa1e681af; asc ;; 11: len 1; hex 30; asc 0;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad04b4b3; asc ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000007; asc ;; 24: SQL NULL; 25: len 12; hex e59cb0e4b88be8bda6e5ba93; asc ;; 26: len 5; hex 99ad040000; asc ;; 27: len 5; hex 99ad0f7efb; asc ~ ;; 28: len 5; hex 6170705f63; asc app_c;; 29: len 30; hex 687474703a2f2f34372e3130332e3133382e38363a31383133392f736d61; asc http://47.103.138.86:18139/sma; (total 85 bytes); 30: len 4; hex 80000000; asc ;;*** (1) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529038 lock mode S waitingRecord lock, heap no 8 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000007; asc ;; 1: len 6; hex 00000129fd49; asc ) I;; 2: len 7; hex 01000002b92c9c; asc , ;; 3: len 9; hex e6b2aa413939393939; asc A99999;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5a594e9a9b0; asc ;; 9: len 6; hex e8939de889b2; asc ;; 10: len 0; hex ; asc ;; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad75403b; asc u@;;; 14: len 5; hex 99ae64dbad; asc d ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303037; asc CO00000007;; 17: len 8; hex 80000000000002dd; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: SQL NULL; 21: SQL NULL; 22: SQL NULL; 23: SQL NULL; 24: SQL NULL; 25: len 0; hex ; asc ;; 26: SQL NULL; 27: SQL NULL; 28: len 2; hex 5043; asc PC;; 29: len 0; hex ; asc ;; 30: len 4; hex 80000000; asc ;;*** (2) TRANSACTION:TRANSACTION 19529033, ACTIVE 0 sec starting index readmysql tables in use 1, locked 1LOCK WAIT 12 lock struct(s), heap size 1128, 60 row lock(s), undo log entries 5MySQL thread id 102078, OS thread handle 140528423110400, query id 14694559 10.0.10.11 root updatingUPDATE info_car SET del_flag = '1' WHERE id = 6*** (2) HOLDS THE LOCK(S):RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529033 lock_mode X locks rec but not gapRecord lock, heap no 8 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000007; asc ;; 1: len 6; hex 00000129fd49; asc ) I;; 2: len 7; hex 01000002b92c9c; asc , ;; 3: len 9; hex e6b2aa413939393939; asc A99999;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5a594e9a9b0; asc ;; 9: len 6; hex e8939de889b2; asc ;; 10: len 0; hex ; asc ;; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad75403b; asc u@;;; 14: len 5; hex 99ae64dbad; asc d ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303037; asc CO00000007;; 17: len 8; hex 80000000000002dd; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: SQL NULL; 21: SQL NULL; 22: SQL NULL; 23: SQL NULL; 24: SQL NULL; 25: len 0; hex ; asc ;; 26: SQL NULL; 27: SQL NULL; 28: len 2; hex 5043; asc PC;; 29: len 0; hex ; asc ;; 30: len 4; hex 80000000; asc ;;*** (2) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529033 lock_mode X locks rec but not gap waitingRecord lock, heap no 7 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000006; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571126; asc W &;; 3: len 9; hex e99995553730363338; asc U70638;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5ae9de9a9ac; asc ;; 9: len 6; hex e799bde889b2; asc ;; 10: len 12; hex e5a487e6b3a8e4bfa1e681af; asc ;; 11: len 1; hex 30; asc 0;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad04b4b3; asc ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000007; asc ;; 24: SQL NULL; 25: len 12; hex e59cb0e4b88be8bda6e5ba93; asc ;; 26: len 5; hex 99ad040000; asc ;; 27: len 5; hex 99ad0f7efb; asc ~ ;; 28: len 5; hex 6170705f63; asc app_c;; 29: len 30; hex 687474703a2f2f34372e3130332e3133382e38363a31383133392f736d61; asc http://47.103.138.86:18139/sma; (total 85 bytes); 30: len 4; hex 80000000; asc ;;*** WE ROLL BACK TRANSACTION (2)------------TRANSACTIONS------------Trx id counter 19530845Purge done for trx's n:o < 19530842 undo n:o < 0 state: running but idleHistory list length 0LIST OF TRANSACTIONS FOR EACH SESSION:---TRANSACTION 422007319659080, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319679280, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319666352, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319651808, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319680896, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319680088, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319649384, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319663928, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319689784, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319688976, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319670392, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319643728, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319688168, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319687360, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319686552, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319684936, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319659888, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319654232, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319684128, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319646960, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319677664, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319675240, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319671200, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319662312, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319651000, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319645344, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319668776, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319656656, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319652616, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319646152, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319676856, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319667160, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319661504, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319657464, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319676048, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319667968, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319674432, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319673624, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319672816, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319648576, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319653424, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319647768, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319642112, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319655848, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319663120, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319642920, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319683320, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319678472, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319644536, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319669584, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319664736, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319660696, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319641304, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319665544, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319655040, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319658272, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319640496, not started0 lock struct(s), heap size 1128, 0 row lock(s)---TRANSACTION 422007319639688, not started0 lock struct(s), heap size 1128, 0 row lock(s)--------FILE I/O--------I/O thread 0 state: waiting for completed aio requests (insert buffer thread)I/O thread 1 state: waiting for completed aio requests (log thread)I/O thread 2 state: waiting for completed aio requests (read thread)I/O thread 3 state: waiting for completed aio requests (read thread)I/O thread 4 state: waiting for completed aio requests (read thread)I/O thread 5 state: waiting for completed aio requests (read thread)I/O thread 6 state: waiting for completed aio requests (write thread)I/O thread 7 state: waiting for completed aio requests (write thread)I/O thread 8 state: waiting for completed aio requests (write thread)I/O thread 9 state: waiting for completed aio requests (write thread)Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] , ibuf aio reads:, log i/o's:, sync i/o's:Pending flushes (fsync) log: 0; buffer pool: 711151794 OS file reads, 7482189 OS file writes, 5555109 OS fsyncs6.20 reads/s, 16384 avg bytes/read, 5.02 writes/s, 4.12 fsyncs/s-------------------------------------INSERT BUFFER AND ADAPTIVE HASH INDEX-------------------------------------Ibuf: size 1, free list len 18, seg size 20, 5848 mergesmerged operations: insert 8619, delete mark 24282, delete 374discarded operations: insert 0, delete mark 0, delete 0Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 237 buffer(s)Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 1 buffer(s)Hash table size 34679, node heap has 7 buffer(s)4810.54 hash searches/s, 217.20 non-hash searches/s---LOG---Log sequence number 5559939411Log buffer assigned up to 5559939411Log buffer completed up to 5559939411Log written up to 5559939411Log flushed up to 5559939411Added dirty pages up to 5559939411Pages flushed up to 5559937109Last checkpoint at 55599371092816524 log i/o's done, 2.17 log i/o's/second----------------------BUFFER POOL AND MEMORY----------------------Total large memory allocated 0Dictionary memory allocated 4523433Buffer pool size 8192Free buffers 1024Database pages 6918Old database pages 2533Modified db pages 52Pending reads 0Pending writes: LRU 0, flush list 0, single page 0Pages made young 196086812, not young 50588523207.84 youngs/s, 9.53 non-youngs/sPages read 1150570, created 58914, written 33764056.20 reads/s, 0.00 creates/s, 1.86 writes/sBuffer pool hit rate 1000 / 1000, young-making rate 13 / 1000 not 0 / 1000Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/sLRU len: 6918, unzip_LRU len: 0I/O sum[129]:cur[298], unzip sum[0]:cur[0]--------------ROW OPERATIONS--------------0 queries inside InnoDB, 0 queries in queue0 read views open inside InnoDBProcess ID=2340, Main thread ID=140531855390464 , state=sleepingNumber of rows inserted 35236029, updated 466521, deleted 68605, read 105179035060.09 inserts/s, 0.45 updates/s, 0.00 deletes/s, 5028.98 reads/sNumber of system rows inserted 89, updated 3784, deleted 44, read 32921740.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s----------------------------END OF INNODB MONITOR OUTPUT============================关键点总结如下：
1.该库中最近一次死锁发生的时间是什么时候？
其中：
=====================================
2022-11-18 14:04:51 140530272577280 INNODB MONITOR OUTPUT
=====================================
这段记录的是查询死锁日志的时间
------------------------
LATEST DETECTED DEADLOCK
------------------------
这段后面记录的就是此次死锁的信息，分为几部分
1、事务1信息
也就是这一部分：
*** (1) TRANSACTION:TRANSACTION 19529038, ACTIVE 0 sec fetching rowsmysql tables in use 15, locked 15LOCK WAIT 44 lock struct(s), heap size 3488, 862 row lock(s), undo log entries 1MySQL thread id 102080, OS thread handle 140528418883328, query id 14694528 10.244.0.216 root executinginsert into _multi_info select * from v_multi_info where id='Vehic9'其中：
TRANSACTION 19529038，是此事务的id。
ACTIVE 0 sec，活跃时间0秒。
mysql tables in use 15, locked 15，表示此事务修改了十五个表，锁了十五行数据。
MySQL thread id 102080，这是线程id
query id 14694528，这是查询id
10.244.0.216 root executing，数据库ip地址，账号，执行语句。
insert into _multi_info select * from v_multi_info where id=‘Vehic9’，这是正在执行的sql，从视图获取数据插入表中。
部分视图内容
create or replace view backend_for_frontend.v_multi_info as(......省略select concat('Vehic', t.id), car_number, 'VEHICLE', t.community_code, 'SaaTe_R_S_Clouds', now(), t.idfrom info_car as twhere t.del_flag = '0' and car_black = '0'union allselect concat('BlaVe', t.id), car_number, 'BLACKLISTED_VEHICLE', t.community_code, 'SaaTe_R_S_Clouds', now(), t.idfrom info_car as twhere t.del_flag = '0' and car_black = '1'......省略 );2、事务1持有的锁
也就是这段：
*** (1) HOLDS THE LOCK(S):RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529038 lock mode SRecord lock, heap no 2 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000001; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571031; asc W 1;; 3: len 9; hex e6b2aa313233343536; asc 123456;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 9; hex e6af94e4ba9ae8bfaa; asc ;; 9: len 6; hex e7baa2e889b2; asc ;; 10: SQL NULL; 11: len 1; hex 30; asc 0;;其中：
RECORD LOCKS，表示持有的是行级锁。
index PRIMARY，表示锁的是主键索引。
table dcxz_sc_prod.info_car，表示锁的具体是哪个表。
trx id 19529038，事务id，和上面的TRANSACTION相同。
lock mode S，锁模式：共享锁。（X：排他锁，S：共享锁）
3、事务1正在等待的锁
也就是这段：
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529038 lock mode S waitingRecord lock, heap no 8 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000007; asc ;; 1: len 6; hex 00000129fd49; asc ) I;; 2: len 7; hex 01000002b92c9c; asc , ;; 3: len 9; hex e6b2aa413939393939; asc A99999;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5a594e9a9b0; asc ;; 9: len 6; hex e8939de889b2; asc ;; 10: len 0; hex ; asc ;; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad75403b; asc u@;;; 14: len 5; hex 99ae64dbad; asc d ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303037; asc CO00000007;; 17: len 8; hex 80000000000002dd; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: SQL NULL; 21: SQL NULL; 22: SQL NULL; 23: SQL NULL; 24: SQL NULL; 25: len 0; hex ; asc ;; 26: SQL NULL; 27: SQL NULL; 28: len 2; hex 5043; asc PC;; 29: len 0; hex ; asc ;; 30: len 4; hex 80000000; asc ;;其中：
index PRIMARY，表示等待的是主键的锁。
table dcxz_sc_prod.info_car，表示等待的表。
trx id 19529038，当前事务1的id。注意这里不是持有目标锁的事务的id，而是当前事务id。
**lock mode S **，表示目标锁是排它锁。
waiting，表示当前事务正在等待。
后面的0至30，表示等待的行
4、事务2信息
也就是这一段：
*** (2) TRANSACTION:TRANSACTION 19529033, ACTIVE 0 sec starting index readmysql tables in use 1, locked 1LOCK WAIT 12 lock struct(s), heap size 1128, 60 row lock(s), undo log entries 5MySQL thread id 102078, OS thread handle 140528423110400, query id 14694559 10.0.10.11 root updatingUPDATE info_car SET del_flag = '1' WHERE id = 6格式和事务1信息相同。
starting index read，事务当前正在根据索引读取数据。
这个描述还有其他情况：
- 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 102078，表示事务id
UPDATE info_car SET del_flag = ‘1’ WHERE id = 6，表示事务2正在执行的sql。
5、事务2正在持有的锁
也就是这段：
*** (2) HOLDS THE LOCK(S):RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529033 lock_mode X locks rec but not gapRecord lock, heap no 8 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000007; asc ;; 1: len 6; hex 00000129fd49; asc ) I;; 2: len 7; hex 01000002b92c9c; asc , ;; 3: len 9; hex e6b2aa413939393939; asc A99999;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5a594e9a9b0; asc ;; 9: len 6; hex e8939de889b2; asc ;; 10: len 0; hex ; asc ;; 11: len 1; hex 31; asc 1;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad75403b; asc u@;;; 14: len 5; hex 99ae64dbad; asc d ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303037; asc CO00000007;; 17: len 8; hex 80000000000002dd; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: SQL NULL; 21: SQL NULL; 22: SQL NULL; 23: SQL NULL; 24: SQL NULL; 25: len 0; hex ; asc ;; 26: SQL NULL; 27: SQL NULL; 28: len 2; hex 5043; asc PC;; 29: len 0; hex ; asc ;; 30: len 4; hex 80000000; asc ;;lock_mode X，锁模式：排他锁。（X：排他锁，S：共享锁）
but not gap，非间隙锁
6、事务2正在等待的锁
也就是这段：
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 547 page no 6 n bits 184 index PRIMARY of table `dcxz_sc_prod`.`info_car` trx id 19529033 lock_mode X locks rec but not gap waitingRecord lock, heap no 7 PHYSICAL RECORD: n_fields 31; compact format; info bits 0 0: len 8; hex 0000000000000006; asc ;; 1: len 6; hex 0000007fcea3; asc ;; 2: len 7; hex 01000001571126; asc W &;; 3: len 9; hex e99995553730363338; asc U70638;; 4: len 8; hex 8000000000000001; asc ;; 5: SQL NULL; 6: SQL NULL; 7: SQL NULL; 8: len 6; hex e5ae9de9a9ac; asc ;; 9: len 6; hex e799bde889b2; asc ;; 10: len 12; hex e5a487e6b3a8e4bfa1e681af; asc ;; 11: len 1; hex 30; asc 0;; 12: len 8; hex 8000000000000001; asc ;; 13: len 5; hex 99ad04b4b3; asc ;; 14: len 5; hex 99ad7721e3; asc w! ;; 15: SQL NULL; 16: len 10; hex 434f3030303030303138; asc CO00000018;; 17: len 8; hex 8000000000000002; asc ;; 18: len 1; hex 30; asc 0;; 19: len 1; hex 31; asc 1;; 20: len 1; hex 31; asc 1;; 21: SQL NULL; 22: SQL NULL; 23: len 8; hex 8000000000000007; asc ;; 24: SQL NULL; 25: len 12; hex e59cb0e4b88be8bda6e5ba93; asc ;; 26: len 5; hex 99ad040000; asc ;; 27: len 5; hex 99ad0f7efb; asc ~ ;; 28: len 5; hex 6170705f63; asc app_c;; 29: len 30; hex 687474703a2f2f34372e3130332e3133382e38363a31383133392f736d61; asc http://47.103.138.86:18139/sma; (total 85 bytes); 30: len 4; hex 80000000; asc ;;7、死锁处理结果
也就是这段：
*** WE ROLL BACK TRANSACTION (2)
表示MySQL最终决定回滚事务2，也就是上面的事务B，这和上面事务B返回的死锁信息是一致的。
关于MySQL的死锁
MySQL的死锁指的是两个事务互相等待的场景，这种循环等待理论上不会有尽头。
比如事务A持有行1的锁，事务B持有行2的锁，
然后事务A试图获取行2的锁，事务B试图获取行1的锁，
这样事务A要等待事务B释放行2的锁，事务B要等待事务A释放行1的锁，
两个事务互相等待，谁也提交不了。
这种情况下MySQL会选择中断并回滚其中一个事务，使得另一个事务可以提交。
MySQL会记录死锁的日志。
模拟死锁的场景(和上面场景无关)
新建一个表，添加两条数据：
创建两个事务，事务执行的sql分别是：
事务A：
set autocommit=0;update medicine_control set current_count=1 where id='1';update medicine_control set current_count=1 where id='2';COMMIT;事务B：
set autocommit=0;update medicine_control set current_count=2 where id='2';update medicine_control set current_count=2 where id='1';COMMIT;可见，事务A先改id=1的数据再改id=2的数据，事务B相反，先改id=2的数据再改id=1的数据。
两个事务sql的执行顺序如下：
| 步骤 | 事务A | 事务A |
|---|---|---|
| 1 | set autocommit=0; | |
| 2 | update medicine_controlset current_count=1where id=‘1’; | |
| 3 | set autocommit=0; | |
| 4 | update medicine_controlset current_count=2where id=‘2’; | |
| 5 | update medicine_controlset current_count=1where id=‘2’; | |
| 6 | update medicine_controlset current_count=2where id=‘1’; |
对每一步的说明：
1，事务A开始事务。
2，事务A修改id=1的数据，持有了该行的锁。
3，事务B开始事务。
4，事务B修改id=2的数据，持有了该行的锁。
5，事务A试图修改id=2的数据，此行的锁被事务B持有，于是事务A等待事务B释放锁。
事务B提交或回滚都能释放锁。
6，事务B试图修改id=1的数据，此行的锁被事务A持有，于是事务B等待事务A释放锁。
事务A提交或回滚都能释放锁。当执行到这一步时，MySQL会立即检测到死锁，并且中断并回滚其中一个事务。此次回滚的是事务B，执行SQL的返回信息是这样的：
[SQL]update medicine_control set current_count=2 where id=‘1’;
[Err] 1213 - Deadlock found when trying to get lock; try restarting transaction
关于mysql的八种锁
1，行锁（Record Locks）
行锁是作用在索引上的。
2，间隙锁（Gap Locks）
间隙锁是锁住一个区间的锁。
这个区间是一个开区间，范围是从某个存在的值向左直到比他小的第一个存在的值，所以间隙锁包含的内容就是在查询范围内，而又不存在的数据区间。
比如有id分别是1,10,20，要修改id<15的数据，那么生成的间隙锁有以下这些：(-∞,1)，(1,10)，(10,20)，此时若有其他事务想要插入id=11的数据，则需要等待。
间隙锁是不互斥的。
作用是防止其他事务在区间内添加记录，而本事务可以在区间内添加记录，从而防止幻读。
在可重复读这种隔离级别下会启用间隙锁，而在读未提交和读已提交两种隔离级别下，即使使用select … in share mode或select … for update，也不会有间隙锁，无法防止幻读。
3，临键锁（Next-key Locks）
临键锁=间隙锁+行锁，于是临键锁的区域是一个左开右闭的区间。
隔离级别是可重复读时，select … in share mode或select … for update会使用临键锁，防止幻读。普通select语句是快照读，不能防止幻读。
4，共享锁/排他锁（Shared and Exclusive Locks）
共享锁和排它锁都是行锁。共享锁用于事务并发读取，比如select … in share mode。排它锁用于事务并发更新或删除。比如select … for update
5，意向共享锁/意向排他锁（Intention Shared and Exclusive Locks）
意向共享锁和意向排他锁都是表级锁。
官方文档中说，事务获得共享锁前要先获得意向共享锁，获得排它锁前要先获得意向排它锁。
意向排它锁互相之间是兼容的。
6，插入意向锁（Insert Intention Locks）
插入意向锁锁的是一个点，是一种特殊的间隙锁，用于并发插入。
插入意向锁和间隙锁互斥。插入意向锁互相不互斥。
7，自增锁（Auto-inc Locks）
自增锁用于事务中插入自增字段。5.1版本前是表锁，5.1及以后版本是互斥轻量锁。
自增所相关的变量有：
auto_increment_offset，初始值
auto_increment_increment，每次增加的数量
innodb_autoinc_lock_mode，自增锁模式
其中：
innodb_autoinc_lock_mode=0，传统方式，每次都产生表锁。此为5.1版本前的默认配置。
innodb_autoinc_lock_mode=1，连续方式。产生轻量锁，申请到自增锁就将锁释放，simple insert会获得批量的锁，保证连续插入。此为5.2版本后的默认配置。
innodb_autoinc_lock_mode=2，交错锁定方式。不锁表，并发速度最快。但最终产生的序列号和执行的先后顺序可能不一致，也可能断裂。
关于死锁的解锁
InnoDB存储引擎会选择回滚undo量最小的事务
来源地址：https://blog.csdn.net/u010026928/article/details/127925144
