一。準備環(huán)境

1.登錄mysql，設(shè)置鎖等待時間，然后退出。

mysql> set global innodb_lock_wait_timeout=1200;Query OK, 0 rows affected (0.00 sec)

2.再次登錄MySQL。打開第一個session

3.登錄msyql，打開第二個session

2.登錄打開第二個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; #執(zhí)行這條sql，會一直卡住。

4.登錄MySQL，打開第三個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;

看上圖trx_state的狀態(tài)LOCK_WAIT，同時trx_query對應的sql語句，說明執(zhí)行這條sql阻塞了。事務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;

看上圖的lock_status出現(xiàn)了一個WAITING,同時THREAD_ID為57的線程處于等待狀態(tài)。對應的ENGINE_TRANSACTION_ID的值就是a操作的圖字段trx_id的值1755425。

4.還要查看鎖事務的對應關(guān)系，

mysql> select locked_table_name,locked_index,waiting_pid,waiting_lock_id,blocking_lock_id,blocking_pid from sys.innodb_lock_waits;

再次對比下?？梢哉业疥P(guān)系，1等待的事務處理，是被2阻塞了。也就是鎖住了，需要2釋放鎖，1才可以執(zhí)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;

同時，查看waiting_pid跟blocking_pid的值就是線程id，對應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.現(xiàn)在上面圖看不到blocking_pid對應的線程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.通過上圖可以看到。 blocking_pid為15 對應的線程THREAD_PID 為56.

waiting_pid為16 對應的線程THREAD_PID 為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;

從圖上分析，就可以看出blocking_pid，也就是已經(jīng)鎖了執(zhí)行的sql是啥。

附:mysql8.0查看死鎖

記錄工作日常遇到的問題

在mysql5.7、mysql5.8等5系版本中

查看死鎖代碼是

select * from information_schema.innodb_locks;

查看等待鎖的代碼

select * from information_schema.innodb_lock_waits

mysql 8.0中查看死鎖代碼變了

如果繼續(xù)用5.7的代碼會提示報錯

Unknown table ‘INNODB_LOCKS' in information_schema

所以在8.0使用以下代碼

#查看死鎖select * from performance_schema.data_locks;#查看死鎖等待時間select * from performance_schema.data_lock_waits;

然后kill就行了

總結(jié)

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