怎么进行MySQL 5.5 MyISAM表锁测试

这篇文章给大家介绍怎么进行MySQL 5.5 MyISAM表锁测试，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。

对于MyISAM表，加的锁是表级锁；写操作会阻塞读操作，读操作会阻塞写操作，写操作会阻塞写操作；读操作不会阻塞读操作。测试一，会话①的读操作阻塞会话②的写操作

会话①

mysql> create table t2(id tinyint(3) unsigned not null auto_increment,

    ->  name varchar(10) not null,

    ->  primary key(id))

->  engine=myisam auto_increment=8 default charset=gbk;

Query OK, 0 rows affected (0.03 sec)

mysql> insert into t2(name) values(Neo);

Query OK, 1 row affected (0.03 sec)

mysql> insert into t2(name) values(Trinity);

Query OK, 1 row affected (0.00 sec)

mysql> select * from t2;

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

| id | name    |

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

|  8 | Neo     |

|  9 | Trinity |

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

2 rows in set (0.00 sec)

mysql> desc t2;

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

| Field | Type                | Null | Key | Default | Extra          |

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

| id    | tinyint(3) unsigned | NO   | PRI | NULL    | auto_increment |

| name  | varchar(10)         | NO   |     | NULL    |                |

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

2 rows in set (0.09 sec)

为表增加读锁

mysql> lock table t2 read;

Query OK, 0 rows affected (0.00 sec)

会话②

mysql> select * from t2;

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

| id | name    |

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

|  8 | Neo     |

|  9 | Trinity |

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

2 rows in set (0.00 sec)

会话会处于等待状态

mysql> update t2 set name=James where id=5;

会话①

mysql> show processlist;

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

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

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

|  1 | system user     |           | NULL | Connect | 748155 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL                                  |

|  2 | system user     |           | NULL | Connect | 748156 | Connecting to master                                                        | NULL                                  |

| 13 | event_scheduler | localhost | NULL | Daemon  | 600105 | Waiting on empty queue                                                      | NULL                                  |

| 74 | neo             | localhost | fire | Query   |      0 | NULL                                                                        | show processlist                      |

| 75 | neo             | localhost | fire | Query   |     83 | Waiting for table level lock                                                | update t2 set name=James where id=5 |

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

5 rows in set (0.00 sec)

mysql> unlock tables;

Query OK, 0 rows affected (0.00 sec)

会话②

mysql> update t2 set name=James where id=5;

Query OK, 0 rows affected (1 min 48.96 sec)

Rows matched: 0  Changed: 0  Warnings: 0

测试二，会话①的写操作阻塞会话②的读操作

会话①

mysql> lock table t2 write;

Query OK, 0 rows affected (0.00 sec)

mysql> insert into t2(name) values(Jack);

Query OK, 1 row affected (0.01 sec)

mysql> commit;

Query OK, 0 rows affected (0.00 sec)

mysql> show processlist;

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

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

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

|  1 | system user     |           | NULL | Connect | 748422 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL             |

|  2 | system user     |           | NULL | Connect | 748423 | Connecting to master                                                        | NULL             |

| 13 | event_scheduler | localhost | NULL | Daemon  | 600372 | Waiting on empty queue                                                      | NULL             |

| 74 | neo             | localhost | fire | Query   |      0 | NULL                                                                        | show processlist |

| 75 | neo             | localhost | fire | Query   |      2 | Waiting for table metadata lock                                             | select * from t2 |

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

5 rows in set (0.00 sec)

会话②

查询会阻塞

mysql> select * from t2;

会话①

mysql> unlock tables;

Query OK, 0 rows affected (0.00 sec)

会话②

mysql> select * from t2;

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

| id | name    |

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

|  8 | Neo     |

|  9 | Trinity |

| 10 | Jack    |

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

3 rows in set (47.89 sec)

当同一个会话中，锁定一张表后，查询另外一张表会报错

mysql> lock table test read;

Query OK, 0 rows affected (0.00 sec)

mysql> select * from test where id=80;

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

| id   | name |

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

|   80 | Lily |

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

1 row in set (0.00 sec)

mysql> select * from t70;

ERROR 1100 (HY000): Table t70 was not locked with LOCK TABLES

使用表的别名会报错

mysql> lock table test read;

Query OK, 0 rows affected (0.00 sec)

mysql> select * from test t where id=80;

ERROR 1100 (HY000): Table t was not locked with LOCK TABLES

需要对别名进行锁定

mysql> lock table test t read;

Query OK, 0 rows affected (0.00 sec)

mysql> select * from test t where id=80;

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

| id   | name |

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

|   80 | Kame |

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

1 row in set (0.00 sec)

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