mysql事务未提交导致锁等待如何解决

1、实验环境

Myql版本5.7.17-log

实验表结构

(root@localhost)[apex]> show create table test;+-------+-----------------------------------------------------------------------------------------------------------------------------------+| Table| Create Table                                                                                                                     |+-------+-----------------------------------------------------------------------------------------------------------------------------------+|test  | CREATE TABLE `test` (  `x` int(11) NOT NULL,  `y` int(11) DEFAULT NULL,  PRIMARY KEY (`x`))ENGINE=InnoDB DEFAULT CHARSET=gbk |+-------+-----------------------------------------------------------------------------------------------------------------------------------+1 row inset (0.01 sec)

插入数据

(root@localhost)[apex]> insert into test values(1,1);(root@localhost)[apex]> insert into test values(2,2);(root@localhost)[apex]> insert into test values(3,3);

2、锁产生步骤

会话一：开启事务，更新数据，不提交

(root@localhost)[apex]> begin;QueryOK, 0 rows affected (0.00 sec)(root@localhost)[apex]> update test set y=y+1 where x=1;QueryOK, 1 row affected (0.00 sec)Rowsmatched: 1  Changed: 1  Warnings: 0

查看当前连接id号（线程id号）

(root@localhost)[apex]> select connection_id();+-----------------+|connection_id() |+-----------------+|               4 |+-----------------+1 row inset (0.00 sec)

会话二：开启另一个事务，更新同一行数据，

(root@localhost)[apex]> begin;QueryOK, 0 rows affected (0.00 sec) (root@localhost)[apex]> update test set y=y+1 where x=1;ERROR1205 (HY000): Lock wait timeout exceeded; try restarting transaction

执行update test set操作时，会卡在那边，不执行，经过50秒后，会报错；

（上面的卡住现象，是由于锁，可以通过查看表information_schema.innodb_lock，获取锁的状态）

(root@localhost)[information_schema]> select * from information_schema.innodb_locks;+-----------------+-------------+-----------+-----------+---------------+------------+------------+-----------+----------+-----------+|lock_id         | lock_trx_id | lock_mode| lock_type | lock_table    | lock_index| lock_space | lock_page | lock_rec | lock_data |+-----------------+-------------+-----------+-----------+---------------+------------+------------+-----------+----------+-----------+|757082:3279:3:2 | 757082      | X         | RECORD    | `apex`.`test` | PRIMARY    |      3279 |         3 |       2 | 1         ||757081:3279:3:2 | 757081      | X         | RECORD    | `apex`.`test` | PRIMARY    |      3279 |         3 |        2 | 1         |+-----------------+-------------+-----------+-----------+---------------+------------+------------+-----------+----------+-----------+2 rowsin set, 1 warning (0.00 sec)

查看当前连接id号（线程id号）

 (root@localhost) [apex]> selectconnection_id();+-----------------+|connection_id() |+-----------------+|               5 |+-----------------+1 row inset (0.00 sec)

以上说的50秒，是系统参数innodb_lock_wait_timeout决定的

(root@localhost)[apex]> show variables like 'innodb_lock_wait_timeout';+--------------------------+-------+|Variable_name            | Value |+--------------------------+-------+| innodb_lock_wait_timeout|  50  |+--------------------------+-------+1 row inset (0.00 sec)

3、mysql 如何查看未提交的事务

方法一：

(root@localhost)[performance_schema]>  SELECT * FROMinformation_schema.INNODB_TRX\G***************************1. row ***************************                    trx_id: 756996                 trx_state: RUNNING               trx_started: 2017-05-08 15:08:07     trx_requested_lock_id: NULL          trx_wait_started: NULL                trx_weight: 3       trx_mysql_thread_id: 4                 trx_query: NULL       trx_operation_state: NULL         trx_tables_in_use: 0         trx_tables_locked: 1          trx_lock_structs: 2     trx_lock_memory_bytes: 1136           trx_rows_locked: 1         trx_rows_modified: 1   trx_concurrency_tickets: 0       trx_isolation_level: REPEATABLE READ         trx_unique_checks: 1    trx_foreign_key_checks: 1trx_last_foreign_key_error:NULL trx_adaptive_hash_latched: 0 trx_adaptive_hash_timeout: 0          trx_is_read_only: 0trx_autocommit_non_locking:01 row inset (0.00 sec)

通过以上可看出线程id为4 一直未提交，事务开始的时间为2017-05-08 15:08:07。

方法二：通过 show engine innodb status\G

其中有一段关于事务的描述

TRANSACTIONS------------Trx idcounter 756998Purgedone for trx's n:o < 0 undo n:o < 0 state: running but idleHistorylist length 0LIST OFTRANSACTIONS FOR EACH SESSION:---TRANSACTION421519065333360, not started0 lockstruct(s), heap size 1136, 0 row lock(s)---TRANSACTION421519065332448, not started0 lockstruct(s), heap size 1136, 0 row lock(s)---TRANSACTION756996, ACTIVE 914 sec2 lockstruct(s), heap size 1136, 1 row lock(s), undo log entries 1MySQL thread id 4, OS thread handle 140041791522560, query id25 localhost root

从以上也可以看出线程id号为4的事务一直未提交。

4、如何解决未提交的事务

方法一：如果能知道哪个用户在执行这个操作，让他提交一下（这种可能性很小）

方法二：kill掉这个线程id号，让事务回滚，

(root@localhost)[information_schema]> show processlist;+----+-----------------+------------------+--------------------+---------+------+------------------------+------------------+| Id |User            | Host             | db                 | Command | Time | State                  | Info             |+----+-----------------+------------------+--------------------+---------+------+------------------------+------------------+|  1 | event_scheduler | localhost        | NULL               | Daemon  | 4469 | Waiting on empty queue | NULL             ||  4 | root            | localhost        | apex               | Sleep   |  871|                        | NULL             ||  5 | root            | localhost        | apex               | Sleep   |   82|                        | NULL             ||  6 | root            | localhost        | information_schema | Query   |    0| starting               | showprocesslist ||  7 | root            | 192.168.1.1:3708 | NULL               | Sleep   | 3221 |                        | NULL             |+----+-----------------+------------------+--------------------+---------+------+------------------------+------------------+5 rowsin set (0.00 sec) (root@localhost)[information_schema]> kill 4;QueryOK, 0 rows affected (0.01 sec)