【0】核心表

　　sys.`innodb_lock_waits`

　　performance_schema.events_statements_history

　　performance_schema.data_locks

　　performance_schema.data_locks_wait

【1】查看锁信息

　　performance_schema.data_locks

　　performance_schema.data_locks_wait

线上mysql版本为8.0.11，对于最近的几个版本越来越像Orale了，有了较为丰富的系统字典，也可以查看系统的等待事件，现在线上出现被锁语句的情况也可以通过数据字典直接查询出来了，在此记录下以供参考。

首先查看系统锁情况，下面这条语句可以看到持有锁的线程以及线程ID，这里需要注意下，session_id也就是show processlist查询出来的链接ID，在这个表里表现为PID，同时该表也记录了trx_id，最后还给出了解决方案也就是如何kill持有锁的进程。

　　

 

 

 
mysql> SELECT * FROM sys.`innodb_lock_waits` \G
 
*************************** 1. row ***************************
 
wait_started: 2019-01-28 14:27:03
 
wait_age: 00:00:03
 
wait_age_secs: 3
 
locked_table: `test`.`t`
 
locked_table_schema: test
 
locked_table_name: t
 
locked_table_partition: NULL
 
locked_table_subpartition: NULL
 
locked_index: GEN_CLUST_INDEX
 
locked_type: RECORD
 
waiting_trx_id: 19758723
 
waiting_trx_started: 2019-01-28 14:27:03
 
waiting_trx_age: 00:00:03
 
waiting_trx_rows_locked: 1
 
waiting_trx_rows_modified: 0
 
waiting_pid: 4202
 
waiting_query: update t set id=8
 
waiting_lock_id: 19758723:4998:4:2
 
waiting_lock_mode: X
 
blocking_trx_id: 19748728
 
blocking_pid: 4200
 
blocking_query: NULL
 
blocking_lock_id: 19748728:4998:4:2
 
blocking_lock_mode: X
 
blocking_trx_started: 2019-01-28 10:58:27
 
blocking_trx_age: 03:28:39
 
blocking_trx_rows_locked: 2
 
blocking_trx_rows_modified: 1
 
sql_kill_blocking_query: KILL QUERY 4200
 
sql_kill_blocking_connection: KILL 4200
 
1 row in set (0.02 sec

 

【2】查看当前被锁的语句

 
##等待锁的语句
 
SELECT * FROM performance_schema.events_statements_history WHERE thread_id IN(
 
SELECT b.`THREAD_ID` FROM sys.`innodb_lock_waits` AS a , performance_schema.threads AS b
 
WHERE a.waiting_pid = b.`PROCESSLIST_ID`)
 
ORDER BY timer_start ASC;

 

 

【3】看持有锁的语句

可以通过如下方式

##持有锁的语句
 
SELECT * FROM performance_schema.events_statements_history WHERE thread_id IN(
 
SELECT b.`THREAD_ID` FROM sys.`innodb_lock_waits` AS a , performance_schema.threads AS b
 
WHERE a.`blocking_pid` = b.`PROCESSLIST_ID`)
 
ORDER BY timer_start ASC;

 

 

大部分转自：https://www.pianshen.com/article/3307195897/