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:
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