mysql8查看锁信息
一。准备环境
1.登录mysql，设置锁等待时间，然后退出。
mysql> set global innodb_lock_wait_timeout=1200;Query OK, 0 rows affected (0.00 sec)
2.再次登录MySQL。打开第一个session
3.登录msyql，打开第二个session
2.登录打开第二个sessionmysql> set autocommit=0;Query OK, 0 rows affected (0.00 sec)mysql> mysql> select @@autocommit;+--------------+| @@autocommit |+--------------+| 0 |+--------------+1 row in set (0.00 sec)mysql> use testmysql> update temp set name='bb' where id=1; #执行这条sql，会一直卡住。
4.登录MySQL，打开第三个session。
a：查看
mysql> select trx_id,trx_state,trx_started,trx_tables_locked,trx_rows_locked,trx_query from information_schema.innodb_trx;
看上图trx_state的状态LOCK_WAIT，同时trx_query对应的sql语句，说明执行这条sql阻塞了。事务id的字段trx_id的值1755425
b：查看
mysql> select ENGINE_LOCK_ID,ENGINE_TRANSACTION_ID,LOCK_MODE,LOCK_TYPE,INDEX_NAME,OBJECT_SCHEMA,OBJECT_NAME,LOCK_DATA,LOCK_STATUS,THREAD_ID from performance_schema.data_locks;
看上图的lock_status出现了一个WAITING,同时THREAD_ID为57的线程处于等待状态。对应的ENGINE_TRANSACTION_ID的值就是a操作的图字段trx_id的值1755425。
4.还要查看锁事务的对应关系，
mysql> select locked_table_name,locked_index,waiting_pid,waiting_lock_id,blocking_lock_id,blocking_pid from sys.innodb_lock_waits;
再次对比下。可以找到关系，1等待的事务处理，是被2阻塞了。也就是锁住了，需要2释放锁，1才可以执行
mysql> select ENGINE_LOCK_ID,ENGINE_TRANSACTION_ID,LOCK_MODE,LOCK_TYPE,INDEX_NAME,OBJECT_SCHEMA,OBJECT_NAME,LOCK_DATA,LOCK_STATUS,THREAD_ID from performance_schema.data_locks;mysql> select locked_table_name,locked_index,waiting_pid,waiting_lock_id,blocking_lock_id,blocking_pid from sys.innodb_lock_waits;
同时，查看waiting_pid跟blocking_pid的值就是线程id，对应processlist
mysql> select locked_table_name,locked_index,waiting_pid,waiting_lock_id,blocking_lock_id,blocking_pid from sys.innodb_lock_waits;mysql> show processlist;
5.现在上面图看不到blocking_pid对应的线程THREAD_PID
mysql> select ENGINE_LOCK_ID,ENGINE_TRANSACTION_ID,LOCK_MODE,LOCK_TYPE,INDEX_NAME,OBJECT_SCHEMA,OBJECT_NAME,LOCK_DATA,LOCK_STATUS,THREAD_ID from performance_schema.data_locks;mysql> select locked_table_name,locked_index,waiting_pid,waiting_lock_id,blocking_lock_id,blocking_pid from sys.innodb_lock_waits;
6.通过上图可以看到。blocking_pid为15 对应的线程THREAD_PID 为56.
waiting_pid为16对应的线程THREAD_PID 为57.
mysql> select THREAD_ID,EVENT_ID,EVENT_NAME,SQL_TEXT from performance_schema.events_statements_history where THREAD_ID in (56,57) order by THREAD_ID,EVENT_ID;
从图上分析，就可以看出blocking_pid，也就是已经锁了执行的sql是啥。
附:mysql8.0查看死锁
记录工作日常遇到的问题
在mysql5.7、mysql5.8等5系版本中
查看死锁代码是
select * from information_schema.innodb_locks;
查看等待锁的代码
select * from information_schema.innodb_lock_waits
mysql 8.0中查看死锁代码变了
如果继续用5.7的代码会提示报错
Unknown table ‘INNODB_LOCKS' in information_schema
所以在8.0使用以下代码
#查看死锁select * from performance_schema.data_locks;#查看死锁等待时间select * from performance_schema.data_lock_waits;
然后kill就行了
总结
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