php关于mysql长连接问题

1、当函数 mysql_connect 的前三个参数（server username password）相同，并且第四个参数（new_link）不传递时候，重复调用 mysql_connect 是会返回相同的连接。

php代码

<?php

$db = mysql_connect('localhost','root','root');

var_dump($db);

$db2 = mysql_connect('localhost','root','root');

var_dump($db2);

sleep(10);

页面打印信息

resource(3) of type (mysql link) resource(3) of type (mysql link)

mysql连接数

mysql> show full processlist;

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

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

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

| 32 | root | localhost:54408 | NULL | Query   |    0 | NULL  | show full processlist |

| 44 | root | localhost:55278 | NULL | Sleep   |    3 |       | NULL                  |

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

2 rows in set

2、当函数 mysql_connect 传递了第四个参数（new_link）后，再重复调用它。

php代码

<?php

$db = mysql_connect('localhost','root','root',1);

var_dump($db);

$db2 = mysql_connect('localhost','root','root',1);

var_dump($db2);

sleep(10);

页面打印信息

resource(3) of type (mysql link) resource(5) of type (mysql link)

mysql连接数

mysql> show full processlist;

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

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

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

| 32 | root | localhost:54408 | NULL | Query   |    0 | NULL  | show full processlist |

| 45 | root | localhost:55320 | NULL | Sleep   |    4 |       | NULL                  |

| 46 | root | localhost:55321 | NULL | Sleep   |    4 |       | NULL                  |

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

3、mysql_pconnect 持久连接

php代码

<?php

$db = mysql_pconnect('localhost','root','root');

var_dump($db);

$db2 = mysql_pconnect('localhost','root','root');

var_dump($db2);

页面打印信息

resource(3) of type (mysql link persistent) resource(4) of type (mysql link persistent)

mysql连接数

mysql> show full processlist;

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

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

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

|  1 | root | localhost:55391 | NULL | Query   |    0 | NULL  | show full processlist |

|  2 | root | localhost:55393 | NULL | Sleep   |    5 |       | NULL                  |

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

4、mysql_pconnect 加上第四个参数（new_link）即可建立多个持久连接

php代码

<?php

$db = mysql_pconnect('localhost','root','root',1);

var_dump($db);

$db2 = mysql_pconnect('localhost','root','root',1);

var_dump($db2);

页面打印信息

resource(3) of type (mysql link persistent) resource(4) of type (mysql link persistent)

mysql连接数

mysql> show full processlist;

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

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

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

|  1 | root | localhost:55391 | NULL | Query   |    0 | NULL  | show full processlist |

|  2 | root | localhost:55393 | NULL | Sleep   |  316 |       | NULL                  |

|  3 | root | localhost:55418 | NULL | Sleep   |    4 |       | NULL                  |

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

3 rows in set

5、总结：

函数 mysql_pconnetc 创建的持久化连接在php脚本结束后，mysql的连接并不会立即结束。什么时候结束，是由mysql自己管理。函数 mysql_colse 不能关闭 mysql_pconnetc 的连接。

函数 mysql_connetc 创建的连接在php脚本结束后，mysql的连接也会相应结束。

巴特西

php关于mysql长连接问题

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