MYSQL死锁相关查找_MySQL
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2024-02-10 17:57:16
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MYSQL死锁相关查找
如果遇到死锁了,怎么解决呢?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,这个问题很好解决。 直接从数据字典连查找。
我们来演示下。
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。
[sql] 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; +----+--------+--------+------------+----+----+----+ | id | fname | lname | birthday | c1 | c2 | c3 | +----+--------+--------+------------+----+----+----+ | 19 | lily19 | lucy19 | 2013-04-18 | 19 | 0 | 0 | | 20 | lily20 | lucy20 | 2013-03-13 | 20 | 0 | 0 | +----+--------+--------+------------+----+----+----+ 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(); +-----------------+ | connection_id() | +-----------------+ | 16 | +-----------------+ 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?
[sql] 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; +--------------+ | @@autocommit | +--------------+ | 1 | +--------------+ 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(); +-----------------+ | connection_id() | +-----------------+ | 17 | +-----------------+ 1 row in set (0.00 sec) mysql> show processlist; +----+------+-----------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+------+---------+------+-------+------------------+ | 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 | +----+------+-----------+------+---------+------+-------+------------------+ 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 = 189325, sees
上面的信息很繁多,也看不清楚到底哪里是哪里。
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。
[sql] 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>
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