确定元数据锁阻塞源，根据相关表关联查询： mysql> SELECT -> p.id AS ID, -> p.user as USER, -> t.PROCESSLIST_DB AS DB_NAME, -> m.OBJECT_NAME AS TABLE_NAME, -> t.PROCESSLIST_TIME AS SPEND_TIME, -> t.PROCESSLIST_INFO AS SQL_TEXT, -> m.LOCK_TYPE AS LOCK_TYPE, -> m.LOCK_STATUS as LOCK_STATUS -> FROM -> information_schema.processlist p -> JOIN -> performance_schema.threads t -> ON -> p.id=t.PROCESSLIST_ID -> JOIN -> performance_schema.metadata_locks m -> ON -> m.OWNER_THREAD_ID=t.THREAD_ID -> WHERE -> m.OBJECT_SCHEMA='test1' and m.OBJECT_NAME='t_ddl'\G *************************** 1. row *************************** ID: 52 USER: root DB_NAME: test1 TABLE_NAME: t_ddl SPEND_TIME: 1176 SQL_TEXT: alter table t_ddl add c int, algorithm=instant LOCK_TYPE: SHARED_UPGRADABLE LOCK_STATUS: GRANTED *************************** 2. row *************************** ID: 52 USER: root DB_NAME: test1 TABLE_NAME: t_ddl SPEND_TIME: 1176 SQL_TEXT: alter table t_ddl add c int, algorithm=instant LOCK_TYPE: EXCLUSIVE LOCK_STATUS: PENDING *************************** 3. row *************************** ID: 54 USER: root DB_NAME: test1 TABLE_NAME: t_ddl SPEND_TIME: 1146 SQL_TEXT: select * from t_ddl limit 1 LOCK_TYPE: SHARED_READ LOCK_STATUS: PENDING *************************** 4. row *************************** ID: 55 USER: root DB_NAME: test1 TABLE_NAME: t_ddl SPEND_TIME: 1187 SQL_TEXT: select * from t_ddl limit 1 for update LOCK_TYPE: SHARED_WRITE LOCK_STATUS: GRANTED 4 rows in set (0.02 sec) 可以查看到阻塞源是select * from t_ddl limit 1 for update，kill 55杀掉阻塞源。