Web缓存原理(三)
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 http://www.chedong.com:81/phpMan.php/man/kill/1
This is ApacheBench, Version 1.3d <$Revision: 1.1 $> apache-1.3
Copyright © 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright © 1998-2001 The Apache Group, http://www.apache.org/
Benchmarking localhost (be patient)…..done
Server Software: Apache/1.3.23
Server Hostname: localhost
Server Port: 80
Document Path: /phpMan.php/man/kill/1
Document Length: 4655 bytes
Concurrency Level: 5
Time taken for tests: 63.164 seconds
Complete requests: 50
Failed requests: 0
Broken pipe errors: 0
Total transferred: 245900 bytes
HTML transferred: 232750 bytes
Requests per second: 0.79 [#/sec] (mean)
Time per request: 6316.40 [ms] (mean)
Time per request: 1263.28 [ms] (mean, across all concurrent requests)
Transfer rate: 3.89 [Kbytes/sec] received
Connnection Times (ms)
min mean[+/-sd] median max
Connect: 0 29 106.1 0 553
Processing: 2942 6016 1845.4 6227 10796
Waiting: 2941 5999 1850.7 6226 10795
Total: 2942 6045 1825.9 6227 10796
Percentage of the requests served within a certain time (ms)
50% 6227
66% 7069
75% 7190
80% 7474
90% 8195
95% 8898
98% 9721
99% 10796
100% 10796 (last request)
测试2:SQUID缓存输出
/home/apache/bin/ab -n50 -c5 “http://localhost:8000/phpMan.php/man/kill/1″
This is ApacheBench, Version 1.3d <$Revision: 1.1 $> apache-1.3
Copyright © 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright © 1998-2001 The Apache Group, http://www.apache.org/
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
结论:对于可能被缓存请求的页面,服务器速度可以有2个数量级的提高,因为SQUID是把缓存页面放在内存里的(因此几乎没有硬盘I/O操作)。
小节:
- 大访问量的网站应尽可能将动态网页生成静态页面作为缓存发布,甚至对于搜索引擎这样的动态应用来说,缓存机制也是非常非常重要的。
- 在动态页面中利用HTTP Header定义缓存更新策略。
- 利用缓存服务器获得额外的配置和安全性
- 日志非常重要:SQUID日志缺省不支持COMBINED日志,但对于需要REFERER日志的这个补丁非常重要:http://www.squid-cache.org/mail-archive/squid-dev/200301/0164.html
参考资料:
HTTP代理缓存
http://vancouver-webpages.com/proxy.html
可缓存的页面设计
http://linux.oreillynet.com/pub/a/linux/2002/02/28/cachefriendly.html
相关RFC文档:
- RFC 2616:
- section 13 (Caching)
- section 14.9 (Cache-Control header)
- section 14.21 (Expires header)
- section 14.32 (Pragma: no-cache) is important if you are interacting with HTTP/1.0 caches
- section 14.29 (Last-Modified) is the most common validation method
- section 3.11 (Entity Tags) covers the extra validation method
可缓存性检查:
http://www.web-caching.com/cacheability.html
缓存设计要素:
http://vancouver-webpages.com/CacheNow/detail.html
ZOPE上的几篇使用APACHE MOD_PROXY MOD_GZIP加速的文档
http://www.zope.org/Members/anser/apache_zserver/
http://www.zope.org/Members/softsign/ZServer_and_Apache_mod_gzip
http://www.zope.org/Members/rbeer/caching

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