通过开启Apache的Keep-Alive属性来支持php对mysql的持久连接

php对mysql的持久连接函数为：mysql_pconnect()

/etc/httpd/conf/httpd.conf # 需要在Apache的配置文件设置几个参数

# KeepAlive: Whether or not to allow persistent connections (more than one request per connection). Set to "Off" to deactivate.

Keep-Alive on

# MaxKeepAliveRequests: The maximum number of requests to allow during a persistent connection. Set to 0 to allow an unlimited amount. We recommend you leave this number high, for maximum performance.

MaxKeepAliveRequests 0

# KeepAliveTimeout: Number of seconds to wait for the next request from the same client on the same connection.

KeepAliveTimeout 15 # 客户端发送HTTP请求成功之后，Apache将不会立刻断开socket，而是一直监听客户端这一请求，持续时间为15秒，如果超过这一时间，Apache就立即断开socket。

注意：Apache的版本为2.0以上。