PHP是不是没有CACHE？

[超级大笨狼]

真要做内存缓存，非分布式，是不是只能在APPLICATION这个对象中做？

[helloDongXiu]

用session保存数据也可以做缓存的吧

[超级大笨狼]

session对应的不是单个用户的COOKIE吗？可以做全局缓存？
[Quote=引用 1 楼 的回复:]

用session保存数据也可以做缓存的吧
[/Quote]

[黄袍披身]

memcache 可以在本地使用呀

[coder]

PHP APC

这个东西是在那个地方缓存的呢?

http://hi.baidu.com/%C1%F9%B9%AB%D7%D32010/blog/item/9de98794d92a9c92a877a452.html

[伴老思源]

<?php 

class cache_memcache { 

    private $_memcached; 
    protected $_memcached_conf = array( 
        'default_host' => '127.0.0.1', 
        'default_port' => 11211, 
        'default_weight' => 1, 
    ); 

    public function __construct() { 

        $this->_memcached = new Memcache($this->_memcached_conf); 
        $this->_memcached->addserver('127.0.0.1', '11211'); 
    } 

    // Save data into cache 
    public function save($key, $data, $ttl = 3600) { 
        if (get_class($this->_memcached) == 'Memcached') { 
            return $this->_memcached->set($key, array($data, time(), $ttl), $ttl); 
        } else if (get_class($this->_memcached) == 'Memcache') { 
            return $this->_memcached->set($key, array($data, time(), $ttl), 0, $ttl); 
        } 

        return false; 
    } 

    // Fetch data from cache 

    public function get($key) { 
        $data = $this->_memcached->get($key); 
        return (is_array($data)) ? $data[0] : false; 
    } 

    // Detele data from cache 
    public function delete($key) { 
        return $this->_memcached->delete($key); 
    } 

    //  // clean will marks all the items as expired, so occupied memory will be overwritten by new items. 
    public function clean() { 
        return $this->_memcached->flush(); 
    } 

    public function ServerStatus() { 
        $server_status = $this->_memcached->getstats(); 
        echo "<table border='1'>"; 
        echo "<tr><td>Memcache Server version:</td><td> " . $server_status["version"] . "</td></tr>"; 
        echo "<tr><td>Process id of this server process </td><td>" . $server_status["pid"] . "</td></tr>"; 
        echo "<tr><td>Number of seconds this server has been running </td><td>" . $server_status["uptime"] . "</td></tr>"; 
        echo "<tr><td>Accumulated user time for this process </td><td>" . $server_status["rusage_user"] . " seconds</td></tr>"; 
        echo "<tr><td>Accumulated system time for this process </td><td>" . $server_status["rusage_system"] . " seconds</td></tr>";
        echo "<tr><td>Total number of items stored by this server ever since it started </td><td>" . $server_status["total_items"] . "</td></tr>"; 
        echo "<tr><td>Number of open connections </td><td>" . $server_status["curr_connections"] . "</td></tr>"; 
        echo "<tr><td>Total number of connections opened since the server started running </td><td>" . $server_status["total_connections"] . "</td></tr>"; 
        echo "<tr><td>Number of connection structures allocated by the server </td><td>" . $server_status["connection_structures"] . "</td></tr>"; 
        echo "<tr><td>Cumulative number of retrieval requests </td><td>" . $server_status["cmd_get"] . "</td></tr>"; 
        echo "<tr><td> Cumulative number of storage requests </td><td>" . $server_status["cmd_set"] . "</td></tr>"; 
        $percCacheHit = ((real) $server_status["get_hits"] / (real) $server_status["cmd_get"] * 100); 
        $percCacheHit = round($percCacheHit, 3); 
        $percCacheMiss = 100 - $percCacheHit; 
        echo "<tr><td>Number of keys that have been requested and found present </td><td>" . $server_status["get_hits"] . " ($percCacheHit%)</td></tr>"; 
        echo "<tr><td>Number of items that have been requested and not found </td><td>" . $server_status["get_misses"] . "($percCacheMiss%)</td></tr>"; 
        $MBRead = (real) $server_status["bytes_read"] / (1024 * 1024); 
        echo "<tr><td>Total number of bytes read by this server from network </td><td>" . $MBRead . " Mega Bytes</td></tr>"; 
        $MBWrite = (real) $server_status["bytes_written"] / (1024 * 1024); 
        echo "<tr><td>Total number of bytes sent by this server to network </td><td>" . $MBWrite . " Mega Bytes</td></tr>"; 
        $MBSize = (real) $server_status["limit_maxbytes"] / (1024 * 1024); 
        echo "<tr><td>Number of bytes this server is allowed to use for storage.</td><td>" . $MBSize . " Mega Bytes</td></tr>"; 
        echo "<tr><td>Number of valid items removed from cache to free memory for new items.</td><td>" . $server_status["evictions"] . "</td></tr>"; 
        echo "</table>"; 
    } 

} 

?>

[helloDongXiu]

网摘php缓存技术：
普遍缓存技术
数据缓存：这里所说的数据缓存是指数据库查询缓存，每次访问页面的时候,都会先检测相应的缓存数据是否存在，如果不存在，就连接数据库，得到数据，并把查询结果序列化后保存到文件中，以后同样的查询结果就直接从缓存表或文件中获得。
用的最广的例子看Discuz的搜索功能，把结果ID缓存到一个表中，下次搜索相同关键字时先搜索缓存表。
举个常用的方法，多表关联的时候，把附表中的内容生成数组保存到主表的一个字段中，需要的时候数组分解一下，这样的好处是只读一个表，坏处就是两个数据同步会多不少步骤，数据库永远是瓶颈，用硬盘换速度，是这个的关键点。
页面缓存：
每次访问页面的时候，都会先检测相应的缓存页面文件是否存在，如果不存在，就连接数据库，得到数据，显示页面并同时生成缓存页面文件，这样下次访问的时候页面文件就发挥作用了。(模板引擎和网上常见的一些缓存类通常有此功能)
时间触发缓存：
检查文件是否存在并且时间戳小于设置的过期时间,如果文件修改的时间戳比当前时间戳减去过期时间戳大，那么就用缓存，否则更新缓存。
内容触发缓存：
当插入数据或更新数据时，强制更新缓存。
静态缓存：
这里所说的静态缓存是指静态化，直接生成HTML或XML等文本文件，有更新的时候重生成一次，适合于不太变化的页面，这就不说了。
以上内容是代码级的解决方案，我直接CP别的框架，也懒得改，内容都差不多，很容易就做到，而且会几种方式一起用，但下面的内容是服务器端的缓存方案，非代码级的，要有多方的合作才能做到
内存缓存:
Memcached是高性能的，分布式的内存对象缓存系统，用于在动态应用中减少数据库负载，提升访问速度。
这里说下Memcached的例子：
代码

<?php
$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");
$version = $memcache->getVersion();
echo "Server's version: ".$version."\n";
$tmp_object = new stdClass;
$tmp_object->str_attr = 'test';
$tmp_object->int_attr = 123;
$memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server");
echo "Store data in the cache (data will expire in 10 seconds)\n";
$get_result = $memcache->get('key');
echo "Data from the cache:\n";
var_dump($get_result);
?>

读库的例子：
代码

<?php
$sql = 'SELECT * FROM users';
$key = md5($sql);   //memcached 对象标识符
if ( !($datas = $mc->get($key)) ) {
    //  在 memcached 中未获取到缓存数据，则使用数据库查询获取记录集。
    echo "n".str_pad('Read datas from MySQL.', 60, '_')."n";
    $conn = mysql_connect('localhost', 'test', 'test');
    mysql_select_db('test');
    $result = mysql_query($sql);
    while ($row = mysql_fetch_object($result))
        $datas[] = $row;
    //  将数据库中获取到的结果集数据保存到 memcached 中，以供下次访问时使用。
    $mc->add($key, $datas);
} else {
    echo "n".str_pad('Read datas from memcached.', 60, '_')."n";
}
var_dump($datas);
?>

php的缓冲器：
有eaccelerator， apc， phpa，xcache，这个这个就不说了吧，搜索一堆一堆的，自己看啦，知道有这玩意就OK
MYSQL缓存：
这也算非代码级的，经典的数据库就是用的这种方式，看下面的运行时间，0.09xxx之类的
我贴段根据蓝色那家伙修改后部分my.ini吧，2G的MYISAM表可以在0.05S左右，据说他前后改了有快一年
代码

[client]
……
default-character-set=gbk
default-storage-engine=MYISAM
max_connections=600
max_connect_errors=500
back_log=200
interactive_timeout=7200
query_cache_size=64M
……
table_cache=512
……
myisam_max_sort_file_size=100G
myisam_max_extra_sort_file_size=100G
myisam_sort_buffer_size=128M
key_buffer_size=1024M
read_buffer_size=512M
……
thread_concurrency=8

基于反向代理的Web缓存:
如Nginx，SQUID，mod_proxy(apache2以上又分为mod_proxy和mod_cache)
NGINX的例子

代码

<nginx.conf>
#user  nobody;
worker_processes  4;
error_log  logs/error.log crit;
pid        logs/nginx.pid;
worker_rlimit_nofile 10240;
events {
    use epoll;
    worker_connections  51200;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile    on;
    keepalive_timeout 65;
    tcp_nodelay on;
    # server pool
    upstream bspfrontsvr {
            server 10.10.10.224:80   weight=1;
            server 10.10.10.221:80   weight=1;
    }
   
    upstream bspimgsvr {
            server 10.10.10.201:80   weight=1;
    }
   
    upstream bspstylesvr {
            server 10.10.10.202:80   weight=1;
    }
   
    upstream bsphelpsvr {
            server 10.10.10.204:80   weight=1;
    }
   
    upstream bspwsisvr {
            server 10.10.10.203:80   weight=1;
    }
   
    upstream bspadminsvr {
            server 10.10.10.222:80   weight=1;
    }
   
    upstream bspbuyersvr {
            server 10.10.10.223:80   weight=1;
    }
   
    upstream bspsellersvr {
            server 10.10.10.225:80   weight=1;
    }
    upstream  bsploginsvr  {
            server 10.10.10.220:443  weight=1;
    }
    upstream  bspregistersvr  {
            server 10.10.10.220:80  weight=1;
    }
    log_format  test_com  '$remote_addr - $remote_user [$time_local] "$request" '
                             '$status $body_bytes_sent "$http_referer" "$http_user_agent" ';
    #--------------------------------------------------------------------
    #img.test.com
    server {
        listen       10.10.10.230:80;
        server_name  img.test.com;
        location / {
                        proxy_pass      http://bspimgsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/img.log  test_com;
    }
   
    #style.test.com
    server {
        listen       10.10.10.230:80;
        server_name  style.test.com;
        location / {
                        proxy_pass      http://bspstylesvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/style.log  test_com;
    }
   
   
    #help.test.com
    server {
        listen       10.10.10.230:80;
        server_name  help.test.com;
        location / {
                        proxy_pass      http://bsphelpsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/help.log  test_com;
    }
   
   
    #admin.test.com
    server {
        listen       10.10.10.230:80;
        server_name  admin.test.com;
        location / {
                        proxy_pass      http://bspadminsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/admin.log  test_com;
    }
   
    #buyer.test.com
    server {
        listen       10.10.10.230:80;
        server_name  buyer.test.com;
        location / {
                        proxy_pass      http://bspbuyersvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/buyer.log  test_com;
    }
   
    #seller.test.com
    server {
        listen       10.10.10.230:80;
        server_name  seller.test.com;
        location / {
                        proxy_pass      http://bspsellersvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/seller.log  test_com;
    }
    #wsi.test.com
    server {
        listen       10.10.10.230:80;
        server_name  wsi.test.com;
        location / {
                        proxy_pass      http://bspwsisvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/wsi.log  test_com;
    }
    #www.test.com
    server {
        listen       10.10.10.230:80;
        server_name  www.test.com   *.test.com;
        location ~ ^/NginxStatus/ {
            stub_status on;
            access_log off;
        }
        location / {
                        proxy_pass      http://bspfrontsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/www.log  test_com;
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }  
    #login.test.com
    server {
        listen       10.10.10.230:443;
        server_name  login.test.com;
        ssl                  on;
        ssl_certificate      cert.pem;
        ssl_certificate_key  cert.key;
        ssl_session_timeout  5m;
        ssl_protocols  SSLv2 SSLv3 TLSv1;
        ssl_ciphers  ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
        ssl_prefer_server_ciphers   on;
        location / {
                        proxy_pass        https://bsploginsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/login.log  test_com;
    }
    #login.test.com for register
    server {
        listen       10.10.10.230:80;
        server_name  login.test.com;
        location / {
                        proxy_pass        http://bspregistersvr;
                        include         proxy_setting.conf;
        }   
        access_log  logs/register.log  test_com;
    }  
   
}
<conf/proxy_setting.conf>
                        proxy_redirect          off;
                        proxy_set_header        Host $host;
                        proxy_set_header        X-Real-IP $remote_addr;
                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                        client_max_body_size    10m;
                        client_body_buffer_size 128k;
                        proxy_connect_timeout   90;
                        proxy_send_timeout      90;
                        proxy_read_timeout      90;
                        proxy_buffer_size       4k;
                        proxy_buffers           4 32k;
                        proxy_busy_buffers_size 64k;
                        proxy_temp_file_write_size 64k;

mod_proxy的例子：

代码

<VirtualHost *>
ServerName www.zxsv.com
ServerAdmin [e-mail]
# reverse proxy setting
ProxyPass / http://www.zxsv.com:8080/
ProxyPassReverse / http://www.zxsv.com:8080/
# cache dir root
CacheRoot "/var/www/proxy"
# max cache storage
CacheSize 50000000
# hour: every 4 hour 
CacheGcInterval 4
# max page expire time: hour
CacheMaxExpire 240
# Expire time = (now - last_modified) * CacheLastModifiedFactor 
CacheLastModifiedFactor 0.1
# defalt expire tag: hour
CacheDefaultExpire 1
# force complete after precent of content retrived: 60-90%
CacheForceCompletion 80
CustomLog /usr/local/apache/logs/dev_access_log combined
</VirtualHost>

而SQUID的例子 ，这方面网上有写的太多，大家自己搜索一下
DNS轮询：
BIND是一款开放源码的DNS服务器软件，这个要说起来就大了，自己搜索去，大家知道有这个东西就行了。
我知道的有chinacache等大站就是这样做的，说简单点就是多服务器啦，把同一个页面或文件缓存到不同的服务器上，按南北自动解析到相关的服务器中

[helloDongXiu]

网摘php缓存技术：
普遍缓存技术
数据缓存：这里所说的数据缓存是指数据库查询缓存，每次访问页面的时候,都会先检测相应的缓存数据是否存在，如果不存在，就连接数据库，得到数据，并把查询结果序列化后保存到文件中，以后同样的查询结果就直接从缓存表或文件中获得。
用的最广的例子看Discuz的搜索功能，把结果ID缓存到一个表中，下次搜索相同关键字时先搜索缓存表。
举个常用的方法，多表关联的时候，把附表中的内容生成数组保存到主表的一个字段中，需要的时候数组分解一下，这样的好处是只读一个表，坏处就是两个数据同步会多不少步骤，数据库永远是瓶颈，用硬盘换速度，是这个的关键点。
页面缓存：
每次访问页面的时候，都会先检测相应的缓存页面文件是否存在，如果不存在，就连接数据库，得到数据，显示页面并同时生成缓存页面文件，这样下次访问的时候页面文件就发挥作用了。(模板引擎和网上常见的一些缓存类通常有此功能)
时间触发缓存：
检查文件是否存在并且时间戳小于设置的过期时间,如果文件修改的时间戳比当前时间戳减去过期时间戳大，那么就用缓存，否则更新缓存。
内容触发缓存：
当插入数据或更新数据时，强制更新缓存。
静态缓存：
这里所说的静态缓存是指静态化，直接生成HTML或XML等文本文件，有更新的时候重生成一次，适合于不太变化的页面，这就不说了。
以上内容是代码级的解决方案，我直接CP别的框架，也懒得改，内容都差不多，很容易就做到，而且会几种方式一起用，但下面的内容是服务器端的缓存方案，非代码级的，要有多方的合作才能做到
内存缓存:
Memcached是高性能的，分布式的内存对象缓存系统，用于在动态应用中减少数据库负载，提升访问速度。
这里说下Memcached的例子：
代码

<?php
$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");
$version = $memcache->getVersion();
echo "Server's version: ".$version."\n";
$tmp_object = new stdClass;
$tmp_object->str_attr = 'test';
$tmp_object->int_attr = 123;
$memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server");
echo "Store data in the cache (data will expire in 10 seconds)\n";
$get_result = $memcache->get('key');
echo "Data from the cache:\n";
var_dump($get_result);
?>

读库的例子：
代码

<?php
$sql = 'SELECT * FROM users';
$key = md5($sql);   //memcached 对象标识符
if ( !($datas = $mc->get($key)) ) {
    //  在 memcached 中未获取到缓存数据，则使用数据库查询获取记录集。
    echo "n".str_pad('Read datas from MySQL.', 60, '_')."n";
    $conn = mysql_connect('localhost', 'test', 'test');
    mysql_select_db('test');
    $result = mysql_query($sql);
    while ($row = mysql_fetch_object($result))
        $datas[] = $row;
    //  将数据库中获取到的结果集数据保存到 memcached 中，以供下次访问时使用。
    $mc->add($key, $datas);
} else {
    echo "n".str_pad('Read datas from memcached.', 60, '_')."n";
}
var_dump($datas);
?>

php的缓冲器：
有eaccelerator， apc， phpa，xcache，这个这个就不说了吧，搜索一堆一堆的，自己看啦，知道有这玩意就OK
MYSQL缓存：
这也算非代码级的，经典的数据库就是用的这种方式，看下面的运行时间，0.09xxx之类的
我贴段根据蓝色那家伙修改后部分my.ini吧，2G的MYISAM表可以在0.05S左右，据说他前后改了有快一年
代码

[client]
……
default-character-set=gbk
default-storage-engine=MYISAM
max_connections=600
max_connect_errors=500
back_log=200
interactive_timeout=7200
query_cache_size=64M
……
table_cache=512
……
myisam_max_sort_file_size=100G
myisam_max_extra_sort_file_size=100G
myisam_sort_buffer_size=128M
key_buffer_size=1024M
read_buffer_size=512M
……
thread_concurrency=8

基于反向代理的Web缓存:
如Nginx，SQUID，mod_proxy(apache2以上又分为mod_proxy和mod_cache)
NGINX的例子

代码

<nginx.conf>
#user  nobody;
worker_processes  4;
error_log  logs/error.log crit;
pid        logs/nginx.pid;
worker_rlimit_nofile 10240;
events {
    use epoll;
    worker_connections  51200;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile    on;
    keepalive_timeout 65;
    tcp_nodelay on;
    # server pool
    upstream bspfrontsvr {
            server 10.10.10.224:80   weight=1;
            server 10.10.10.221:80   weight=1;
    }
   
    upstream bspimgsvr {
            server 10.10.10.201:80   weight=1;
    }
   
    upstream bspstylesvr {
            server 10.10.10.202:80   weight=1;
    }
   
    upstream bsphelpsvr {
            server 10.10.10.204:80   weight=1;
    }
    upstream bspwsisvr {
            server 10.10.10.203:80   weight=1;
    }
   
    upstream bspadminsvr {
            server 10.10.10.222:80   weight=1;
    }
   
    upstream bspbuyersvr {
            server 10.10.10.223:80   weight=1;
    }
   
    upstream bspsellersvr {
            server 10.10.10.225:80   weight=1;
    }
    upstream  bsploginsvr  {
            server 10.10.10.220:443  weight=1;
    }
    upstream  bspregistersvr  {
            server 10.10.10.220:80  weight=1;
    }
    log_format  test_com  '$remote_addr - $remote_user [$time_local] "$request" '
                             '$status $body_bytes_sent "$http_referer" "$http_user_agent" ';
    #--------------------------------------------------------------------
    #img.test.com
    server {
        listen       10.10.10.230:80;
        server_name  img.test.com;
        location / {
                        proxy_pass      http://bspimgsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/img.log  test_com;
    }
   
    #style.test.com
    server {
        listen       10.10.10.230:80;
        server_name  style.test.com;
        location / {
                        proxy_pass      http://bspstylesvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/style.log  test_com;
    }
   
   
    #help.test.com
    server {
        listen       10.10.10.230:80;
        server_name  help.test.com;
        location / {
                        proxy_pass      http://bsphelpsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/help.log  test_com;
    }
   
   
    #admin.test.com
    server {
        listen       10.10.10.230:80;
        server_name  admin.test.com;
        location / {
                        proxy_pass      http://bspadminsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/admin.log  test_com;
    }
   
    #buyer.test.com
    server {
        listen       10.10.10.230:80;
        server_name  buyer.test.com;
        location / {
                        proxy_pass      http://bspbuyersvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/buyer.log  test_com;
    }
   
    #seller.test.com
    server {
        listen       10.10.10.230:80;
        server_name  seller.test.com;
        location / {
                        proxy_pass      http://bspsellersvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/seller.log  test_com;
    }
    #wsi.test.com
    server {
        listen       10.10.10.230:80;
        server_name  wsi.test.com;
        location / {
                        proxy_pass      http://bspwsisvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/wsi.log  test_com;
    }
    #www.test.com
    server {
        listen       10.10.10.230:80;
        server_name  www.test.com   *.test.com;
        location ~ ^/NginxStatus/ {
            stub_status on;
            access_log off;
        }
        location / {
                        proxy_pass      http://bspfrontsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/www.log  test_com;
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }  
    #login.test.com
    server {
        listen       10.10.10.230:443;
        server_name  login.test.com;
        ssl                  on;
        ssl_certificate      cert.pem;
        ssl_certificate_key  cert.key;
        ssl_session_timeout  5m;
        ssl_protocols  SSLv2 SSLv3 TLSv1;
        ssl_ciphers  ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
        ssl_prefer_server_ciphers   on;
        location / {
                        proxy_pass        https://bsploginsvr;
                        include         proxy_setting.conf;
        }
        access_log  logs/login.log  test_com;
    }
    #login.test.com for register
    server {
        listen       10.10.10.230:80;
        server_name  login.test.com;
        location / {
                        proxy_pass        http://bspregistersvr;
                        include         proxy_setting.conf;
        }   
        access_log  logs/register.log  test_com;
    }  
   
}
<conf/proxy_setting.conf>
                        proxy_redirect          off;
                        proxy_set_header        Host $host;
                        proxy_set_header        X-Real-IP $remote_addr;
                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                        client_max_body_size    10m;
                        client_body_buffer_size 128k;
                        proxy_connect_timeout   90;
                        proxy_send_timeout      90;
                        proxy_read_timeout      90;
                        proxy_buffer_size       4k;
                        proxy_buffers           4 32k;
                        proxy_busy_buffers_size 64k;
                        proxy_temp_file_write_size 64k;

mod_proxy的例子：

代码

<VirtualHost *>
ServerName www.zxsv.com
ServerAdmin [e-mail]
# reverse proxy setting
ProxyPass / http://www.zxsv.com:8080/
ProxyPassReverse / http://www.zxsv.com:8080/
# cache dir root
CacheRoot "/var/www/proxy"
# max cache storage
CacheSize 50000000
# hour: every 4 hour 
CacheGcInterval 4
# max page expire time: hour
CacheMaxExpire 240
# Expire time = (now - last_modified) * CacheLastModifiedFactor 
CacheLastModifiedFactor 0.1
# defalt expire tag: hour
CacheDefaultExpire 1
# force complete after precent of content retrived: 60-90%
CacheForceCompletion 80
CustomLog /usr/local/apache/logs/dev_access_log combined
</VirtualHost>

而SQUID的例子 ，这方面网上有写的太多，大家自己搜索一下
DNS轮询：
BIND是一款开放源码的DNS服务器软件，这个要说起来就大了，自己搜索去，大家知道有这个东西就行了。
我知道的有chinacache等大站就是这样做的，说简单点就是多服务器啦，把同一个页面或文件缓存到不同的服务器上，按南北自动解析到相关的服务器中

[qq120848369]

可以配置session存储在memcache里, 数据缓存直接用memached, redis都行, 页面缓存用ob+缓存.