《MysqL必读查找MysqL线程中死锁的ID的方法》要点：
本文介绍了MysqL必读查找MysqL线程中死锁的ID的方法，希望对您有用。如果有疑问，可以联系我们。
如果遇到死锁了,怎么办理呢?找到原始的锁ID,然后KILL掉一直持有的那个线程就可以了,但是众多线程,可怎么找到引起死锁的线程ID呢? MysqL 发展到现在,已经非常强大了,这个问题很好办理. 直接从数据字典连查找.MysqL教程
我们来演示下.MysqL教程
线程A,我们用来锁定某些记录,假设这个线程一直没提交,或者忘掉提交了. 那么就一直存在,但是数据里面显示的只是SLEEP状态.MysqL教程
MysqL> set @@autocommit=0; Query OK,0 rows affected (0.00 sec) MysqL> use test; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed MysqL> show tables; +―――――-+ | Tables_in_test | +―――――-+ | demo_test | | t3 | +―――――-+ 2 rows in set (0.00 sec) MysqL> select * from t3; +―-+――C+――C+――――+―-+―-+―-+ | id | fname | lname | birthday | c1 | c2 | c3 | +―-+――C+――C+――――+―-+―-+―-+ | 19 | lily19 | lucy19 | 2013-04-18 | 19 | 0 | 0 | | 20 | lily20 | lucy20 | 2013-03-13 | 20 | 0 | 0 | +―-+――C+――C+――――+―-+―-+―-+ 2 rows in set (0.00 sec) MysqL> update t3 set birthday = '2022-02-23' where id = 19; Query OK,1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 MysqL> select connection_id(); +―――――C+ | connection_id() | +―――――C+ | 16 | +―――――C+ 1 row in set (0.00 sec) MysqL>
线程B,我们用来进行普通的更新,但是遇到问题了,此时不知道是哪个线程把这行记录给锁定了?MysqL教程
MysqL> use test; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed MysqL> select @@autocommit; +――――C+ | @@autocommit | +――――C+ | 1 | +――――C+ 1 row in set (0.00 sec) MysqL> update t3 set birthday='2018-01-03' where id = 19; ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction MysqL> select connection_id(); +―――――C+ | connection_id() | +―――――C+ | 17 | +―――――C+ 1 row in set (0.00 sec) MysqL> show processlist; +―-+――+―――C+――+―――+――+――-+――――――+ | Id | User | Host | db | Command | Time | State | Info | +―-+――+―――C+――+―――+――+――-+――――――+ | 10 | root | localhost | NULL | Sleep | 1540 | | NULL | | 11 | root | localhost | NULL | Sleep | 722 | | NULL | | 16 | root | localhost | test | Sleep | 424 | | NULL | | 17 | root | localhost | test | Query | 0 | init | show processlist | | 18 | root | localhost | NULL | Sleep | 5 | | NULL | +―-+――+―――C+――+―――+――+――-+――――――+ 5 rows in set (0.00 sec) MysqL> show engine innodb status\G ―――― TRANSACTIONS ―――― Trx id counter 189327 Purge done for trx's n:o < 189323 undo n:o < 0 state: running but idle History list length 343 LIST OF TRANSACTIONS FOR EACH SESSION: ―TRANSACTION 0,not started MysqL thread id 11,OS thread handle 0x7f70a0c98700,query id 994 localhost root init show engine innodb status ―TRANSACTION 189326,ACTIVE 2 sec starting index read MysqL tables in use 1,locked 1 LOCK WAIT 2 lock struct(s),heap size 376,1 row lock(s) MysqL thread id 17,OS thread handle 0x7f70a0bd5700,query id 993 localhost root updating update t3 set birthday='2018-01-03' where id = 19 ――- TRX HAS BEEN WAITING 2 SEC FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 529 page no 3 n bits 72 index `PRIMARY` of table `test`.`t3` trx id 189326 lock_mode X waiting Record lock,heap no 2 PHYSICAL RECORD: n_fields 9; compact format; info bits 0 0: len 2; hex 3139; asc 19;; 1: len 6; hex 00000002e38c; asc ;; 2: len 7; hex 7e00000d2827c9; asc ~ (' ;; 3: len 6; hex 6c696c793139; asc lily19;; 4: len 6; hex 6c7563793139; asc lucy19;; 5: len 3; hex 8fcc57; asc W;; 6: len 4; hex 80000013; asc ;; 7: len 4; hex 80000000; asc ;; 8: len 4; hex 80000000; asc ;; ―――――― ―TRANSACTION 189324,ACTIVE 641 sec 2 lock struct(s),3 row lock(s),undo log entries 1 MysqL thread id 16,OS thread handle 0x7f70a0b94700,query id 985 localhost root cleaning up Trx read view will not see trx with id >= 189325,sees < 189325
上面的信息很繁多,也看不清楚到底哪里是哪里.MysqL教程
不过现在,我们只要从数据字典里面拿出来这部分信息就OK了.MysqL教程
MysqL> SELECT * FROM information_schema.INNODB_TRX\G *************************** 1. row *************************** trx_id: 189324 trx_state: RUNNING trx_started: 2013-04-18 17:48:14 trx_requested_lock_id: NULL trx_wait_started: NULL trx_weight: 3 trx_MysqL_thread_id: 16 trx_query: NULL trx_operation_state: NULL trx_tables_in_use: 0 trx_tables_locked: 0 trx_lock_structs: 2 trx_lock_memory_bytes: 376 trx_rows_locked: 3 trx_rows_modified: 1 trx_concurrency_tickets: 0 trx_isolation_level: REPEATABLE READ trx_unique_checks: 1 trx_foreign_key_checks: 1 trx_last_foreign_key_error: NULL trx_adaptive_hash_latched: 0 trx_adaptive_hash_timeout: 10000 trx_is_read_only: 0 trx_autocommit_non_locking: 0 1 row in set (0.01 sec) MysqL>
本来是线程16忘掉COMMIT了.
MysqL教程
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