MySQL 死锁日志分析

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LATEST DETECTED DEADLOCK

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140824 1:01:24

*** (1) TRANSACTION:

TRANSACTION 110E, ACTIVE 73 sec starting index read ## 事务ID=110E，活跃了73s

mysql tables in use 1, locked 1

LOCK WAIT 3 lock struct(s), heap size 376, 2 row lock(s) ## 有2个行锁

MySQL thread id 1, OS thread handle 0x7f55ea639700, query id 81 localhost root updating ## 该事务的线程ID=1

delete from t1 where a=1 ## 这是当前事务执行的SQL

*** (1) WAITING FOR THIS LOCK TO BE GRANTED: ## 上面SQL等待的锁信息

RECORD LOCKS space id 12 page no 3 n bits 80 index `PRIMARY` of table `test`.`t1` trx id 110E lock_mode X locks rec but not gap waiting

Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info bits 32 ## 等待在主键上的page num=3上有加一个X锁(not gap waiting)，锁80 bits

0: len 4; hex 80000001; asc ;;

1: len 6; hex 00000000110c; asc ;;

2: len 7; hex 0d000002350084; asc 5 ;;

3: len 4; hex 80000001; asc ;;

*** (2) TRANSACTION:

TRANSACTION 110C, ACTIVE 1716 sec starting index read, thread declared inside InnoDB 500 ## 事务ID=110C，活跃了1716s

mysql tables in use 1, locked 1

3 lock struct(s), heap size 376, 2 row lock(s), undo log entries 1 ## 3个锁，2个行锁，1个undo log

MySQL thread id 2, OS thread handle 0x7f563c05e700, query id 82 localhost root updating ## 该事务的线程ID=2

delete from t1 where a=3 ## 这是当前事务执行的SQL

*** (2) HOLDS THE LOCK(S): ## 这个事务持有的锁信息

RECORD LOCKS space id 12 page no 3 n bits 80 index `PRIMARY` of table `test`.`t1` trx id 110C lock_mode X locks rec but not gap

Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info bits 32 ## 在主键上的page num=3上已持有一个X锁(not gap)，锁80 bits

0: len 4; hex 80000001; asc ;;

1: len 6; hex 00000000110c; asc ;;

2: len 7; hex 0d000002350084; asc 5 ;;

3: len 4; hex 80000001; asc ;;

*** (2) WAITING FOR THIS LOCK TO BE GRANTED: ## 同时这个事务还等待的锁信息

RECORD LOCKS space id 12 page no 3 n bits 80 index `PRIMARY` of table `test`.`t1` trx id 110C lock_mode X locks rec but not gap waiting

Record lock, heap no 3 PHYSICAL RECORD: n_fields 4; compact format; info bits 0 ## 同样等待在主键上的page num=3上有加一个X锁(not gap waiting)，锁80 bits

0: len 4; hex 80000003; asc ;;

1: len 6; hex 000000000f71; asc q;;

2: len 7; hex ed0000022f0090; asc / ;;

3: len 4; hex 80000003; asc ;;

*** WE ROLL BACK TRANSACTION (1) ## 这里选择回滚了事务110E。

也就是说，这个死锁使用事务110E中的SQL没有执行，回滚了：

delete from t1 where a=1

而事务110C中的SQL是正常被执行的：

delete from t1 where a=3