当mysql 数据库发生死锁时， innodb status 里面会记录最后一次死锁的相关信息，但mysql 错误日志里面
不会记录死锁相关信息，要想记录，启动 innodb_print_all_deadlocks 参数 。
当系统并发很高时，很多的线程等待同一个行锁，死锁检测可能会拖慢系统，这个时候关闭死锁检测可能更好
（innodb_deadlock_detect 5.7.15 版本才有）。让线程自动超时。
mysql> show variables like 'innodb_print_all_deadlocks';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| innodb_print_all_deadlocks | ON |
+----------------------------+-------+2018-07-13T12:57:35.621054+08:00 21018 [Note] InnoDB:
*** (1) TRANSACTION:
TRANSACTION 1344, ACTIVE 9 sec starting index read
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 21019, OS thread handle 139626295346944, query id 42108 localhost root updating
delete from t1 where id=1
2018-07-13T12:57:35.621146+08:00 21018 [Note] InnoDB: *** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 27 page no 3 n bits 72 index PRIMARY of table `test`.`t1` trx id 1344 lock_mode X locks rec but not gap waiting
Record lock, heap no 2 PHYSICAL RECORD: n_fields 3; compact format; info bits 32
0: len 4; hex 80000001; asc ;;
1: len 6; hex 00000000053b; asc ;;;
2: len 7; hex 28000000360110; asc ( 6 ;;
2018-07-13T12:57:35.621428+08:00 21018 [Note] InnoDB: *** (2) TRANSACTION:
TRANSACTION 1339, ACTIVE 35 sec starting index read, thread declared inside InnoDB 5000
mysql tables in use 1, locked 1
3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 21018, OS thread handle 139626295879424, query id 42109 localhost root updating
delete from t1 where id=2
2018-07-13T12:57:35.621532+08:00 21018 [Note] InnoDB: *** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 27 page no 3 n bits 72 index PRIMARY of table `test`.`t1` trx id 1339 lock_mode X locks rec but not gap
Record lock, heap no 2 PHYSICAL RECORD: n_fields 3; compact format; info bits 32
0: len 4; hex 80000001; asc ;;
1: len 6; hex 00000000053b; asc ;;;
2: len 7; hex 28000000360110; asc ( 6 ;;
2018-07-13T12:57:35.621739+08:00 21018 [Note] InnoDB: *** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 27 page no 3 n bits 72 index PRIMARY of table `test`.`t1` trx id 1339 lock_mode X locks rec but not gap waiting
Record lock, heap no 3 PHYSICAL RECORD: n_fields 3; compact format; info bits 32
0: len 4; hex 80000002; asc ;;
1: len 6; hex 000000000540; asc @;;
2: len 7; hex 2b000000300409; asc + 0 ;;
2018-07-13T12:57:35.621965+08:00 21018 [Note] InnoDB: *** WE ROLL BACK TRANSACTION (2)
2018-07-13T12:57:54.527054+08:00 21023 [Note] Access denied for user 'repl'@'10.10.19.202' (using password: YES)