Lighttpd & Modcache

1. Lighttpd & Modcache 2009/06/28

2. Basic lighttpd info Event-driven, single process Uses non-block io (network) + writev (memory) + sendfile (local files) Light weighted, simple module structure Homepage http://redmine.lighttpd.net/projects/lighttpd

3. Lighttpd’s advantages No need to sync data and variables between modules Modern OS/Hardware are so powerful that event-driven model works great Handy conditional configuration Easy to write modules (http://redmine.lighttpd.net/projects/lighttpd/wiki/Devel )

4. Lighttpd’s disadvantages Sometimes one process isn’t enough (try server.max-workers) One block io operation may block whole http service mod_fastcgi doesn’t work as fast as it should be because of poor request distribution algorithm

5. General lighttpd tuning • server.event-handler = "linux-sysepoll“ • server.max-fds = 16384 # set max open fd limit to 16k • server.max-keep-alive-idle = 0 #don’t use keep-alive • server.max-read-idle = 30 # smaller read timeout • server.max-write-idle = 180 # smaller write timeout

6. Mod_fastcgi Tuning server.max-request-size = 40960 #maximum 40M post content length fastcgi.server = ( ".php" => (( "socket" => "/tmp/php-fastcgi.socket", "bin-path" => "/usr/bin/php-cgi -c /etc/php.ini", "max-procs" => 20, "bin-environment" => ( "PHP_FCGI_CHILDREN" => "9", #lighttpd will fork 20*10=200 php-cgi children "PHP_FCGI_MAX_REQUESTS" => "50000“ # php child restart after processing 50k requests ), "broken-scriptfilename" => "enable", "allow-x-send-file" => "enable", "check-local" => "disable", "bin-copy-environment" => ( "PATH", "SHELL", "USER" ) )) )

7. Basic modcache info Project started when squid can’t fulfill need v1.0 released at 10/2006, v1.8 released at 06/2009 Open source, BSD License Supports both disk-based cache and memory-based cache Homepage http://www.linux.com.cn/modcache/

8. Modcache’s advantages Lighttpd based (it’s a powerful web server, far away beyond normal proxy server) Works with other lighttpd modules, such as mod_compress / mod_access Keep it as simple as possible Small source code base (< 3000 lines) Don’t use local db to store cache information

9. Modcache’s disadvantages No internal cache files management (try /usr/sbin/tmpwatch) Rules of cache are controlled by modcache, not by backend servers Memory cache doesn’t share between different lighttpd processes It’s a patch, not included in official lighttpd release

10. Modcache Event based Directories based Without disk management Reverse Cache only No ICP Expire time based on refresh.pattern Conditional config /ACL Small source codebase Squid Thread based DB based With disk management Reverse/Forward Cache Supports ICP Expire time based on backend response and refresh-pattern ACL Large source codebase Modcache vs Squid

11. Modcache config(1) cache.bases List of cache directories. For examples: cache.bases = ("/data/cache", "/data2/cache") cache.domains List of domains which modcache would try to cache for. When it isn’t set, modcache would cache files of every domains. for examples: cache.domains = ("(^|\.)linux\.com\.cn$") caches *.linux.com.cn. domains. cache.ignore-hostname. Includes hostname in saved filename or not. default is disable. cache.debug Default is disable cache.enable Default is enable

12. Modcache config(2) cache.support-queries Try to cache query with '?'. default is 'disable'. When cache.support-queries = "enable" and cache.dynamic-mode = "disable", modcache will treat "/uri?q1" or "/uri?q2" as "/uri" and save them to local cache file of "/uri". When cache.support-queries and cache.dynamic-mode are both enabled, modcache will treat "/uri?q1" and "/uri?q2" as different resource and save them to different local cache files. cache.dynamic-mode To support dynamic generated web page such as forum/bbs. default is "disable". Note: cache.support-queries has to be enabled when dynamic-mode is enabled. cache.programs-ext List of local program extension, such as ".php". modcache will replace them with ".cache.html" to aviod confliction with other modules, such as mod_fastcgi. default is not set

13. Modcache config(3) cache.max-memory-size Number of MBytes which modcache will use to save cached content in memory. default is 256Mbytes. cache.lru-remove-count Number of content removed from memory when memory is full. default is 256. cache.purge-host pcre regex hosts ip which are allowed to PURGE cache files. for examples: cache.purge-host="^200\.100\.1\." allow 200.100.1.0/24 to purge cache. Default is not set

14. Cache.refresh-pattern Key of modcache, idea from squid’s refresh-pattern cache.refresh-pattern format is "url_pcre_regex" => "minutes options". Note: zero 'minutes' means cache forever and minutes option is mandatory.

15. Refresh Pattern options(1) ignore-reload Don't update cache when browser sends 'Cache-Control: no-cache' header. It's default behaviour update-on-refresh Update cache when browser sends 'Cache-Control: no-cache' header. Nocache Don't cache matched url. fetchall-for-range-request Download all content of file if client sends 'Range: xxx-yyybytes' header. Useful for multi-thread downloaders(such as flashget).

16. Refresh Pattern options(2) rfc-violated options: override-expire Ignore backend's 'Expire' header while determining whether to cache. ignore-vary Igore backend’s ‘Vary’ header while determining whether to cache ignore-cache-control-header Ignore backend's 'Cache-Control' headers while determining whether to cache.

17. Refresh Pattern options(3) flv-streaming to work with mod_flv_streaming. memory-compress compress memory-saved content for ‘Accept-Encoding: gzip, deflate’ request use-memory use memory to save caches instead of local disk

18. Modcache Cook Books (1) Site with several millions image files server.modules = ( # ...., # other modules "mod_cache", # make sure mod_cache loaded before mod_proxy "mod_proxy" ) proxy.worked-with-mod-cache = "enable" cache.bases = ("/data/cache") cache.support-queries = "enable" cache.max-memory = 2000 # 2000M suitable for 4G memory server cache.refresh-pattern = ( "\.(?i)(jpg|bmp|jpeg|gif|png|ico)$" => "0 use-memory", #cache for ever until removed from memory "." => "120 " # other uses disk based cache )

19. Modcache Cook Books (2) Softwares/Music/Video download site # uses several separate disks cache.bases = ("/data/cache1", "/data/cache2", "/data/cache3", "/data/cache4") cache.support-queries = "enable" cache.refresh-pattern = ( "\.(?i)(rar|zip|exe|wmv|avi|mp3|ape|rm|mpeg|mpg|wma|asf|rmvb)$" => "10080 fetchall-for-range-request", "." => "120" )

20. Modcache Cook Books (3) BBS Site server.modules = ( "mod_compress", #use it to compress html/css files "mod_cache", "mod_proxy" ) mimetype.assign = ( ".css" => "text/css", ".js" => "application/x-javascript", ".html" => "text/html", ".htm" => "text/html" )

21. Modcache Cook Books (3) BBS Site(continued) # compress output for css/js/html/htm compress.filetype = ("application/x-javascript", "text/css", "text/html") cache.support-queries = "enable" cache.dynamic-mode = "enable" cache.bases = ("/data/cache") cache.refresh-pattern = ( "\.(?i)(js|css|xml)$" => "240", "\.(?i)(htm|html|shtml)$" => "30 ignore-vary", ".(?i)(/|php)$" => "5 use-memory update-on-refresh memory-compress", "." => "30 update-on-refresh" # default to update every 30 minutes and on refresh requests )

22. Modcache Cook Books (4) Video share site server.modules = ( "mod_flv_streaming", "mod_cache", "mod_proxy" ) flv-streaming.extensions = (".flv") cache.bases = ("/data/cache1", "/data/cache2", "/data/cache3“) cache.support-queries = "enable" cache.refresh-pattern = ( "\.(?i)(flv)$" => "0 flv-streaming", # flv_streaming for flv files "." => "120" )

23. Thanks for listening Q&A