lighttpd提供了一个接口,外部程式支持的FastCGI接口，FastCGI是一个独立于平台，和服务器，应用程序独立的一个接口
fastcgi简介:
1:fastcgi消除了很多cgi的局限性,cgi在每个请求完成后会自动重新启动,导致性能不佳
2:fastcig保持进程一直运行并等待请求，消除了fork过程，减少了整体启动和消亡的时间.
3:cgi程序通过管道和服务器进行通讯,fastcgi通过unix套接字或者TCP/IP和服务器进行通讯，也就是说fastcgi选项不仅可以运行于网络服务器本身,而且包括所有的网络
4:fastcgi内部提供了一个负载均衡器，对比apache+mod_php,fastcgi提供的额外安全性,可以运行于不同的权限服务器.
fastcgi模块配置选项:
( "host" => <string> ,
"port" => <integer> ,
"socket" => <string>, # either socket or host+port
"bin-path" => <string>, # optional
"bin-environment" => <array>, # optional
"bin-copy-environment" => <array>, # optional
"mode" => <string>, # optional
"docroot" => <string> , # optional if "mode" is not "authorizer"
"check-local" => <string>, # optional
"min-procs" => <integer>, # optional
"max-procs" => <integer>, # optional
"max-load-per-proc" => <integer>, # optional used for adaptive spawning of fcgi processes for versions below 1.3.14
"idle-timeout" => <integer>, # optional
"broken-scriptfilename" => <boolean>, # optional
"disable-time" => <integer>, # optional
"allow-x-send-file" => <boolean>, # optional
"kill-signal" => <integer>, # optional (v1.4.14+ though option is accepted in earlier versions)
),
host/port:fastcgi进程的host和端口
bin-path:本地fastcgi二进制文件
socket:unix套接字文件
mode:responder和authorizer模式
docroot:出于安全原因，因此建议把这个docroot以外server.document根树
disable-time:等待fasgcgi后端去检查的时间
allow-x-send-file:controls if X-LIGHTTPD-send-file and X-Sendfile headers are allowed
max-procs:设置开始最大的进程数量
max-load-per-proc:在一个新的进程产生之前，平均每个进程可以等待的处理数量
idle-timeout:在一个不可活动进程消亡前可以存活的时间
bin-environment:进程标识符
Load-Balancing:负载均衡
The FastCGI plugin provides automaticly a load-balancing between multiple FastCGI servers
Adaptive Process Spawning
假如你想至少有一个fastcgi进程去处理更多的请求，可以设置min-procs and max-procs.
FastCGI and Programming Languages:
PHP provides 2 special environment variables which control the number of spawned workers under the control of a single watching process (PHP_FCGI_CHILDREN)
and the number of requests what a single worker handles before it kills itself.
fastcgi.server = ( ".php" =>
( "localhost" =>
# "host"=>"127.0.0.1",
#"port"=>4000,
"socket" => "/data/lighttpd/php-fastcgi.socket",
"bin-path" => "/data/lighttpd/fcgi/php",
"check-local"=>"disable",
"min-procs"=>3,
"max-procs"=>10,
"max-load-per-proc" => 4,
"idle-timeout" => 20,
"bin-environment" => (
"PHP_FCGI_CHILDREN" => "16",
"PHP_FCGI_MAX_REQUESTS" => "10000" ),
"bin-copy-environment" => (
"PATH", "SHELL", "USER" )
)
)
num-procs = max-procs * ( 1 + PHP_FCGI_CHILDREN )
10 * (16 + 1) = 170 procs