乐在其中

早先问过BleakWind，他认为，给别人做的话MySQL内存表做会话比较好一些，因为MySQL内存表做Session更容易维护（可以制作 安装脚本）。这个周末，我进行了一些测试，测试MySQL MyISAM表做会话（对时间给不给索引）、内存表做会话、MemCache做会话的效率比较。

定义会话Session类：

<?php

/**

 * @author: wps2000

 * file Session.php

 * Email:[email protected]

 * Data: 16/12/2007

 */

class Seesion {

    const SESSION_ID_NAME = ‘PHPSESSID’;

    /**

     * 会话生成时间

     *

     * @var int

     */

    private $_session_left_time;

    /**

     * 会话GC概率

     *

     * @var int

     */

    private $_gc_probility;

    /**

     * 会话处理器

     *

     * @var Session_Handler_Interface

     */

    private $_session_handler;

    /**

     * 存储的会话数据

     *

     * @var Array

     */

    private $_data;

    /**

     * 会话ID

     *

     * @var String

     */

    private $_session_id;

    public function __construct(Seesion_Handler_Interface $handler) {

       $this->_session_handler = $handler;

       $this->_gc_probility = ( int ) (get_cfg_var ( ‘session.gc_divisor’ ) / get_cfg_var ( ‘session.gc_probability’ ));

       $this->_sessin_left_time = ( int ) get_cfg_var ( ‘session.gc_maxlifetime’ );

       $this->_session_handler->open ( $this->_session_left_time );

       if (isset ( $_COOKIE [self::SESSION_ID_NAME] )) {

           $this->_session_id = $_COOKIE [self::SESSION_ID_NAME];

           $this->_data = $this->_session_handler->read ( $this->_session_id );

       } else {

           $this->_session_id = $this->_generate_session_id ();

           setcookie ( self::SESSION_ID_NAME, $this->_session_id, null, ‘/’ );

       }

    }

    private function _generate_session_id() {

       return uniqid ( mt_rand (), true );

    }

    public function __set($k, $v) {

       $this->_data [$k] = $v;

    }

    public function __get($k) {

       if (isset ( $this->_data [$k] ))

           return $this->_data [$k];

       return null;

    }

    public function destroy() {

       $this->_sessin_handler->destroy ( $this->_session_id );

    }

    public function __destruct() {

       $this->_session_handler->write ( $this->_session_id, $this->_data );

       $this->_session_handler->close ();

       if (mt_rand ( 1, $this->_gc_probility ) == 1) {

           $this->_session_handler->gc ( $this->_session_left_time );

       }

    }

}

?>

定义会话处理器接口（Session_Handler_Interface)：

<?php

/**

 * @package default

 * @author wps2000

 * file Session_Handler_Interface.php

 * Email:[email protected]

 * Date: 16/12/2007

 */

interface Sessin_Handler_Interface {

    function open($life_time);

    function read($id);

    function write($id, Array $data = null);

    function destroy($id);

    function close();

    function gc($time = 0);

}

?>

实现MySQL内存表Session处理器：

<?php

/**

 * @author wps2000

 * file MySQL_Memory_Session.php

 * Email: [email protected]

 * Date: 16/12/2007

 */

class MySQL_Memory_Session implements Sessin_Handler_Interface {

    /**

     * 存储的数据库链接

     *

     * @var PDO

     */

    private $_db;

    private $_life_time;

    public function open($life_time) {

       $this->_db = new PDO ( ‘mysql:host=localhost;dbname=session’, ‘root’, ‘root’, array (PDO::ATTR_PERSISTENT => true, PDO::MYSQL_ATTR_DIRECT_QUERY => true ) );

       $this->_db = query ( ‘set names utf8’ );

       $this->_life_time = $life_time;

    }

    public function read($id) {

       /**

        * 本处未做任何过滤

        */

       $result = $this->_db->query ( ‘select * from `session` where `id`=\” . $id . ‘\’ and `time`>’ . (time () – $this->_life_time) )->fetchAll ( PDO::FETCH_ASSOC );

       if ($result)

           return $result [0];

       return array ();

    }

    public function write($id, Array $data = null) {

       /**

        * 本处未做任何过滤

        */

       $this->_db->query ( ‘replace into `session`(`id`,`name`,`ip`,`time`) values (\” . $id . ‘\’,\” . $data [‘name’] . ‘\’,\” . $data [‘ip’] . ‘\’,’ . time () . ‘)’ );

    }

    public function destroy($id) {

       if (! $time)

           $time = $this->_life_time;

       $this->_db->query ( ‘delete from `session` where `time`<‘ . (time () – $time) );

    }

    public function close() {

       return true;

    }

}

?>

实现MemCache会话处理器：

<?php

/**

 * @author: wps2000

 * file MemCache_Session.php

 * Email:[email protected]

 * Date: 16/12/2007

 * Test via MemCache 1.21 Server,PHP 5.25 with PHP_memcache.dll for PHP5.21

 */

class MemCache_Session implements Sessin_Handler_Interface {

    private $_host;

    private $_life_time;

    public function open($life_time) {

       $this->_host = new MemCache ( );

       $this->_host->pconnect ( ‘localhost’ );

       $this->_life_time = $life_time;

    }

    public function read($id) {

       if ($result = $this->_host->get ( $id ))

           return $result;

       return array ();

    }

    public function write($id, Array $data = null) {

       $this->_host->set ( $id, $data, MEMCACHE_COMPRESSED, $this->_life_time );

    }

    public function destroy($id) {

       $this->_host->delete ( $id );

    }

    public function close() {

       return true;

    }

    public function gc($lift_time = 0) {

       return true;

    }

}

?>

MySQL内存表测试程序：

<?php

/**

 * 测试写入Session

 */

error_reporting ( E_ALL );

require ‘./Session_Handler_Interface.php’;

require ‘./MySQL_Memory_Session.php’;

require ‘./Session.php’;

 

$session = new Seesion ( new MySQL_Memory_Session ( ) );

$session->name = ‘wps2000’;

$session->ip = $_SERVER [‘REMOTE_ADDR’];

echo ‘Yeah!’;

 

?>

MemCache会话测试代码：

<?php

/**

 * 测试MemCache Session实现

 */

require ‘./Session_Handler_Interface.php’;

require ‘./Session.php’;

require ‘./MemCache_Session.php’;

 

$sess = new Seesion ( new MemCache_Session ( ) );

$sess->name = ‘张心灵‘;

$sess->age = 23;

echo ‘Yeah’;

?>

MySQL会话表如下：

CREATE TABLE `session` (
`id` char(32) COLLATE utf8_unicode_ci NOT NULL,
`name` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
`ip` varchar(15) COLLATE utf8_unicode_ci NOT NULL,
`time` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MEMORY DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

测试结果：

MemCache：

======================================================================================

Concurrency Level:      30
Time taken for tests:   18.234375 seconds
Complete requests:      10000
Failed requests:        0
Write errors:           0
Total transferred:      2774781 bytes
HTML transferred:       280000 bytes
Requests per second:    548.41 [#/sec] (mean)
Time per request:       54.703 [ms] (mean)
Time per request:       1.823 [ms] (mean, across all concurrent requests)
Transfer rate:          148.57 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median   max
Connect:        0    0   1.9      0      31
Processing:     0   53 12.1     46     328
Waiting:        0   52 11.9     46     328
Total:          0   53 12.1     46     328

Percentage of the requests served within a certain time (ms)
50%     46
66%     62
75%     62
80%     62
90%     62
95%     62
98%     62
99%     78
100%    328 (longest request)

MySQL内存表：

=================================================================================

Concurrency Level:      30
Time taken for tests:   20.375000 seconds
Complete requests:      10000
Failed requests:        4694
(Connect: 0, Length: 4694, Exceptions: 0)
Write errors:           0
Total transferred:      3118440 bytes
HTML transferred:       623048 bytes
Requests per second:    490.80 [#/sec] (mean)
Time per request:       61.125 [ms] (mean)
Time per request:       2.038 [ms] (mean, across all concurrent requests)
Transfer rate:          149.45 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median   max
Connect:        0    0   1.9      0      31
Processing:     0   60   7.6     62     125
Waiting:        0   59   7.6     62     125
Total:          0   60   7.5     62     125

Percentage of the requests served within a certain time (ms)
50%     62
66%     62
75%     62
80%     62
90%     62
95%     62
98%     78
99%     78
100%    125 (longest request)

其他测试：

将MySQL实现的数据库引擎改为 MyISAM（依然为 并发 30 测试 10000 次） 结果为：

Requests per second:    440.17 [#/sec] (mean)
Percentage of the requests served within a certain time (ms)
50%     62
66%     62
75%     78
80%     78
90%     78
95%     78
98%     78
99%     78
100%    640 (longest request)

为MyISAM表的 time 列增加索引（因为 会话表 读写次数几乎相等，因此应该效果不明显），结果为：

Requests per second:    441.08 [#/sec] (mean)
Percentage of the requests served within a certain time (ms)
50%     62
66%     62
75%     78
80%     78
90%     78
95%     78
98%    109
99%    109
100%    156 (longest request)

=================================================================================

结论：

MemCache做会话效率最高，也最灵活，但目前尝不支持查看谁在线等功能，附加的，只能自己增加一个数组记录在线用户、以及最后活跃时间并实现gc等。
MySQL内存表做会话效率也相当的高，另外一个有点是，MySQL内存表似乎更稳定，longest request （125ms）明显的短于 MemCache的（328ms）。不过缺点是，存储的字段数以及字段长度受限。
MySQL MyISAM表做会话在这里居然也达到了440的rps，真不简单。不过您要是等半个小时在测试一次，您就会明白MyISAM表的缺点了，页面几乎崩溃。MyISAM表的缺点是，一旦其中有较多的碎片，这个数据库几乎都不可用了，您注释掉 gc 的代码在这里貌似可以获得更好的效率表现(^_^、当然也可以定时的Optimizer，概率触发或者Cron定时启动也不错）
MyISAM表对time列增加索引对每秒完成的请求数没什么影响，不过有一点需要注意的是，增加索引后，每次完成 request的时间更均匀了,longest request从640ms跌到了156ms。为time列增加索引有助于让完成请求的时间变均匀。

测试平台：

Acer Aspire 4520G：
CPU：AMD Athlon 64 * 2 TK-55
RAM: IG
OS: Windows XP sp2
Web Server: Apache 2.26
PHP: PHP5.25