MySQL - Lock wait timeout exceeded

　　今天突然出了个奇怪的问题，原本正常启动的项目，在什么都没有修改的情况下，启动到一半的时候会卡住几分钟，几分钟后又成功启动了，刚好是卡在Quartz那里，还以为出什么奇奇怪怪的幺蛾子了，一看日志，数据库锁住了~ 记录一下解决方法。

　　转载 ： http://blog.csdn.net/mchdba/article/details/38313881

　　

1，查看数据库的隔离级别：

mysql> select @@tx_isolation;
+-----------------+
| @@tx_isolation  |
+-----------------+
| REPEATABLE-READ |
+-----------------+
1 row in set (0.00 sec)

mysql>

2，去查看先当前库的线程情况：

mysql> show full processlist;

+----------+-----------------+-------------------+-----------------+-------------+---------+-------------------------+-----------------------+

| Id       | User            | Host              | db              | Command     | Time    | State                   | Info                  |

+----------+-----------------+-------------------+-----------------+-------------+---------+-------------------------+-----------------------+

|        1 | event_scheduler | localhost         | NULL            | Daemon      | 9635385 | Waiting on empty queue  | NULL                  |

|  9930577 | business_web    | 192.168.1.21:45503 | business_db     | Sleep       |     153 |                         | NULL                  |

|  9945825 | business_web    | 192.168.1.25:49518 | business_db     | Sleep       |      43 |                         | NULL                  |

|  9946322 | business_web    | 192.168.1.23:44721 | business_db     | Sleep       |     153 |                         | NULL                  |

|  9960167 | business_web    | 192.168.3.28:2409  | business_db     | Sleep       |      93 |                         | NULL                  |

|  9964484 | business_web    | 192.168.1.21:24280 | business_db     | Sleep       |       7 |                         | NULL                  |

|  9972499 | business_web    | 192.168.3.28:35752 | business_db     | Sleep       |      13 |                         | NULL                  |

| 10000117 | business_web    | 192.168.3.28:9149  | business_db     | Sleep       |       6 |                         | NULL                  |

| 10002523 | business_web    | 192.168.3.29:42872 | business_db     | Sleep       |       6 |                         | NULL                  |

| 10007545 | business_web    | 192.168.1.21:51379 | business_db     | Sleep       |     155 |                         | NULL                  |
......

+----------+-----------------+-------------------+-----------------+-------------+---------+-------------------------+-----------------------+

没有看到正在执行的慢SQL记录线程，再去查看innodb的事务表INNODB_TRX，看下里面是否有正在锁定的事务线程，看看ID是否在show full processlist里面的sleep线程中，如果是，就证明这个sleep的线程事务一直没有commit或者rollback而是卡住了，我们需要手动kill掉。

mysql> SELECT * FROM information_schema.INNODB_TRX\G;

*************************** 1. row ***************************

trx_id: 20866

trx_state: LOCK WAIT

trx_started: 2014-07-31 10:42:35

trx_requested_lock_id: 20866:617:3:3

trx_wait_started: 2014-07-30 10:42:35

trx_weight: 2

trx_mysql_thread_id: 9930577

trx_query: delete from dltask where id=1

trx_operation_state: starting index read

trx_tables_in_use: 1

trx_tables_locked: 1

trx_lock_structs: 2

trx_lock_memory_bytes: 376

trx_rows_locked: 1

trx_rows_modified: 0

trx_concurrency_tickets: 0

trx_isolation_level: READ COMMITTED

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

3，看到有这条9930577的sql，kill掉，执行kill 9930577;

mysql> kill 9930577;

Query OK, 0 rows affected (0.00 sec)

mysql>

然后再去查询INNODB_TRX表，就没有阻塞的事务sleep线程存在了，如下所示：

mysql> SELECT * FROM INNODB_TRX\G;

Empty set (0.00 sec)

ERROR:

No query specified

mysql>

再去执行update语句，就能正常执行了，如下所示：

mysql> update order_info  set province_id=15  ,city_id= 1667  where order_from=10 and order_out_sn='1407261241xxxx';

Query OK, 1 row affected (0.00 sec)

Rows matched: 1  Changed: 1  Warnings: 0

mysql>