【原创】查找原始MySQL死锁ID
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。
[*]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: 1Changed: 1Warnings: 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？
[*]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 < 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), heap size 376, 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。
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> 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>
原来是线程16忘掉COMMIT了。
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