:: 极限 Linux ::基于反向代理的Web缓存加速

基于Apache mod_proxy的反向代理缓存加速实现
Apache包含了mod_proxy模块，可以用来实现代理服务器，针对后台服务器的反向加速
安装apache 1.3.x 编译时：
--enable-shared=max --enable-module=most
注：Apache 2.x中mod_proxy已经被分离成mod_proxy和mod_cache：同时mod_cache有基于文件和基于内存的不同实现
创建/var/www/proxy，设置apache服务所用户可写
mod_proxy配置样例：反相代理缓存＋缓存
架设前台的www.example.com反向代理后台的www.backend.com的8080端口服务。
修改：httpd.conf
<VirtualHost *>
ServerName www.example.com
ServerAdmin admin@example.com
# reverse proxy setting
ProxyPass / http://www.backend.com:8080/
ProxyPassReverse / http://www.backend.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>

基于Squid的反向代理加速实现
Squid是一个更专用的代理服务器，性能和效率会比Apache的mod_proxy高很多。
如果需要combined格式日志补丁：
http://www.squid-cache.org/mail-archive/squid-dev/200301/0164.html
squid的编译：
./configure --enable-useragent-log  --enable-referer-log --enable-default-err-language=Simplify_Chinese --enable-err-languages="Simplify_Chinese English" --disable-internal-dns
make
#make install
#cd /usr/local/squid
make dir cache
chown squid.squid *
vi /usr/local/squid/etc/squid.conf
在/etc/hosts中：加入内部的DNS解析，比如：
192.168.0.4 [url]www.chedong.com[/url]
192.168.0.4 news.chedong.com
192.168.0.3 bbs.chedong.com
---------------------cut here----------------------------------
# visible name
visible_hostname cache.example.com
# cache config: space use 1G and memory use 256M
cache_dir ufs /usr/local/squid/cache 1024 16 256
cache_mem 256 MB
cache_effective_user squid
cache_effective_group squid

http_port 80
httpd_accel_host virtual
httpd_accel_single_host off
httpd_accel_port 80
httpd_accel_uses_host_header on
httpd_accel_with_proxy on
# accelerater my domain only
acl acceleratedHostA dstdomain .example1.com
acl acceleratedHostB dstdomain .example2.com
acl acceleratedHostC dstdomain .example3.com
# accelerater http protocol on port 80
acl acceleratedProtocol protocol HTTP
acl acceleratedPort port 80
# access arc
acl all src 0.0.0.0/0.0.0.0
# Allow requests when they are to the accelerated machine AND to the
# right port with right protocol
http_access allow acceleratedProtocol acceleratedPort acceleratedHostA
http_access allow acceleratedProtocol acceleratedPort acceleratedHostB
http_access allow acceleratedProtocol acceleratedPort acceleratedHostC
# logging
emulate_httpd_log on
cache_store_log none
# manager
acl manager proto cache_object
http_access allow manager all
cachemgr_passwd pass all

----------------------cut here---------------------------------
创建缓存目录：
/usr/local/squid/sbin/squid -z
启动squid
/usr/local/squid/sbin/squid
停止squid：
/usr/local/squid/sbin/squid -k shutdown
启用新配置：
/usr/local/squid/sbin/squid -k reconfig
通过crontab每天0点截断/轮循日志：
0 0 * * * (/usr/local/squid/sbin/squid -k rotate)

附：SQUID性能测试试验

phpMan.php是一个基于php的man page server，每个man
page需要调用后台的man命令和很多页面格式化工具，系统负载比较高，提供了Cache
Friendly的URL，以下是针对同样的页面的性能测试资料：
测试环境：Redhat 8 on Cyrix 266 / 192M Mem
测试程序：使用apache的ab(apache benchmark)：
测试条件：请求50次，并发50个连接
测试项目：直接通过apache 1.3 (80端口) vs squid 2.5(8000端口：加速80端口)

测试1：无CACHE的80端口动态输出：
ab -n 100 -c 10 [url]http://www.chedong.com:81/phpMan.php/man/kill/1[/url]
This is ApacheBench, Version 1.3d <$Revision: 1.2 $> apache-1.3
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd,
[url]http://www.zeustech.net/[/url]
Copyright (c) 1998-2001 The Apache Group, [url]http://www.apache.org/[/url]

Benchmarking localhost (be patient).....done
Server Software:
Apache/1.3.23
Server Hostname:       localhost
Server
Port:
80

Document Path:
/phpMan.php/man/kill/1
Document Length:       4655 bytes

Concurrency Level:    5
Time taken for tests: 63.164 seconds
Complete requests:    50
Failed requests:       0
Broken pipe errors:    0
Total transferred:    245900 bytes
HTML transferred:    232750 bytes
Requests per second: 0.79 [#/sec] (mean)
Time per request:    6316.40 [ms]
(mean)
Time per request:    1263.28 [ms]
(mean, across all concurrent requests)
Transfer rate:
3.89 [Kbytes/sec] received

Connnection Times (ms)

min  mean[+/-sd] median max
Connect:       0
29  106.1    0 553
Processing:  2942  6016
1845.4 6227 10796

Waiting:
2941  5999 1850.7 6226 10795

Total:
2942  6045 1825.9 6227 10796

Percentage of the requests served within a certain time (ms)
  50% 6227
  66% 7069
  75% 7190
  80% 7474
  90% 8195
  95% 8898
  98% 9721
  99%  10796
100%  10796 (last request)

测试2：SQUID缓存输出
/home/apache/bin/ab -n50 -c5
":8000/phpMan.php/man/kill/1"
This is ApacheBench, Version 1.3d <$Revision: 1.2 $> apache-1.3
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd,
[url]http://www.zeustech.net/[/url]
Copyright (c) 1998-2001 The Apache Group, [url]http://www.apache.org/[/url]

Benchmarking localhost (be patient).....done
Server Software:
Apache/1.3.23
Server Hostname:       localhost
Server
Port:
8000

Document Path:
/phpMan.php/man/kill/1
Document Length:       4655 bytes

Concurrency Level:    5
Time taken for tests: 4.265 seconds
Complete requests:    50
Failed requests:       0
Broken pipe errors:    0
Total transferred:    248043 bytes
HTML transferred:    232750 bytes
Requests per second: 11.72 [#/sec] (mean)
Time per request:    426.50 [ms] (mean)
Time per request:    85.30 [ms] (mean,
across all concurrent requests)
Transfer rate:
58.16 [Kbytes/sec] received

Connnection Times (ms)

min  mean[+/-sd] median max
Connect:
0    1
9.5    0 68
Processing:
7 83  537.4
7  3808

Waiting:
5 81  529.1
6  3748

Total:
7 84  547.0
7  3876

Percentage of the requests served within a certain time (ms)
  50%    7
  66%    7
  75%    7
  80%    7
  90%    7
  95%    7
  98%    8
  99% 3876
100% 3876 (last request)

结论：No Cache / Cache = 6045 / 84 = 70