php持久化连接数据库
php的持久化数据库连接已经不是一个新鲜的名词了,由于php语言生命周期的问题,如果每次连接数据库都重新打开一个连接会很低效,所以引入了长连接机制(应该是实现在sapi部分,例如cli sapi就不支持db长连接),本文探究apache2handler sapi和 fpm sapi是否支持db长连接.使用方法以pdo为例在实例化pdo对象时传入:
PDO::ATTR_PERSISTENT => true即可实现长连接,但是隐约在哪里听说过在apache下由于是以线程的方式执行,所以连接在线程关闭时也会释放掉.本着实践是检验真理的唯一标准态度,遂决定做个实验测试下.
测试环境: mysql-5.1.50 php-5.4.19 apache && nginx
php测试代码:
<?php
$pdo = new PDO(
sprintf('mysql:dbname=%s;host=%s;port=%d', 'test', 'localhost', '3306'),
'test',
'test',
array(
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
//PDO::ATTR_PERSISTENT => true #pdo默认为false
)
);
var_dump($pdo->query('select now()')->fetchColumn());测试php-fpm sapi(nginx): 首先查看数据库连接:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
+----+------+-----------------+------+---------+------+-------+-----------------------+
1 row in set (0.00 sec)访问php测试脚本后查看数据库连接:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
+----+------+-----------------+------+---------+------+-------+-----------------------+
1 row in set (0.00 sec)将测试脚本中PDO::ATTR_PERSISTENT => true的注释取消掉后执行脚本,再查看数据库连接:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
| 3 | test | localhost:61525 | test | Sleep | 2 | | NULL |
+----+------+-----------------+------+---------+------+-------+-----------------------+
2 rows in set (0.00 sec)结论1:fpm sapi支持db长连接
测试apache2handler sapi(apache): 首先关闭掉长连接会话:
mysql> kill 3;
Query OK, 0 rows affected (0.00 sec)查看数据库会话列表:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
+----+------+-----------------+------+---------+------+-------+-----------------------+
1 row in set (0.00 sec)执行测试脚本(注释掉PDO::ATTR_PERSISTENT => true,即未设置长连接的脚本)并查看数据库会话:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
+----+------+-----------------+------+---------+------+-------+-----------------------+
1 row in set (0.00 sec)然后执行设置好长连接的脚本并查看数据库会话:
mysql> show full processlist;
+----+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+-------+-----------------------+
| 1 | root | localhost:61513 | test | Query | 0 | NULL | show full processlist |
| 5 | test | localhost:61569 | test | Sleep | 2 | | NULL |
+----+------+-----------------+------+---------+------+-------+-----------------------+
2 rows in set (0.00 sec)结论2:apache2handler sapi也是支持db长连接的
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