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mysql8查看锁
简介mysql8查看锁
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
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event_id
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event_id 为56.
blocking_pid为16 对应的线程event_id 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。
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