Zhiqiang::He

如何降低这些开销呢？fastcgi应用程序已经较好的优化了，耗费的资源很少，而且只有少于10个进程在运行，因此问题不在fastcgi。问题在Apache的并发响应能力，以及资源占用上。

使用lighttpd可以较好的解决这个问题，lighttpd基于单进程多路复用技术，因此消耗的资源非常少。而且支持fastcgi，但由于对php的支持仅限于fastcgi，与机器现有的一些网站并不能很好的兼容，因此考虑前端(80端口)用Apache，后端(2088)用lighttpd，通过rewrite技术，将fastcgi请求转交(Redirect)给后端的lighttpd处理。

这样原理上就能使apache的进程大幅度减少，并只是负责请求的转发而已，可以充分的利用原来的进程资源。而lighttpd消耗的cpu/memory资源也较低，因此完成同样的任务，Apache+lighttpd的方案就比原来的纯Apache要好得多。

实际运行证明，效率要好得多，响应速度提高了一个数量级以上。客户反映良好。

Apache rewrite + lighttpd 实现方法

原来负载较高的网站主机名highload.xxx.com ，运行的fastcgi prefix是/fcgi-bin。因此需要对这个虚拟主机进行Rewrite配置。

第一步，编译apache，激活mod_rewrite：

./configure \
--with-layout=Apache --prefix=/usr/local/httpd \
--enable-shared=max --enable-module=rewrite \
--enable-shared=rewrite

安装并加载好之后，配置highload.xxx.com的虚拟主机，在VirtualHost里增加：

RewriteEngine on
RewriteRule   ^\/fcgi-bin\/(.+)      http://highload.xxx.com:2088/$1

第二步，编译lighttpd，配置fastcgi并使lighttpd监听于2088端口：

./configure --prefix=/usr/local/lighttpd

配置：

server.modules              = (
                               "mod_access",
                               "mod_fastcgi",
                                "mod_accesslog" )

server.document-root    = "/var/www/vhost/highload/fcgi-bin/"
server.errorlog             = "/var/log/lighttpd/lighttpd.error.log"

server.indexfiles           = ( "index.php", "index.html",
                                "index.htm", "default.htm" )

mimetype.assign             = (
  ".pdf"          =>      "application/pdf",
  ".sig"          =>      "application/pgp-signature",
  ".spl"          =>      "application/futuresplash",
  ".class"        =>      "application/octet-stream",
  ".ps"           =>      "application/postscript",
  ".torrent"      =>      "application/x-bittorrent",
  ".dvi"          =>      "application/x-dvi",
  ".gz"           =>      "application/x-gzip",
  ".pac"          =>      "application/x-ns-proxy-autoconfig",
  ".swf"          =>      "application/x-shockwave-flash",
  ".tar.gz"       =>      "application/x-tgz",
  ".tgz"          =>      "application/x-tgz",
  ".tar"          =>      "application/x-tar",
  ".zip"          =>      "application/zip",
  ".mp3"          =>      "audio/mpeg",
  ".m3u"          =>      "audio/x-mpegurl",
  ".wma"          =>      "audio/x-ms-wma",
  ".wax"          =>      "audio/x-ms-wax",
  ".ogg"          =>      "audio/x-wav",
  ".wav"          =>      "audio/x-wav",
  ".gif"          =>      "image/gif",
  ".jpg"          =>      "image/jpeg",
  ".jpeg"         =>      "image/jpeg",
  ".png"          =>      "image/png",
  ".xbm"          =>      "image/x-xbitmap",
  ".xpm"          =>      "image/x-xpixmap",
  ".xwd"          =>      "image/x-xwindowdump",
  ".css"          =>      "text/css",
  ".html"         =>      "text/html",
  ".htm"          =>      "text/html",
  ".js"           =>      "text/javascript",
  ".asc"          =>      "text/plain",
  ".c"            =>      "text/plain",
  ".conf"         =>      "text/plain",
  ".text"         =>      "text/plain",
  ".txt"          =>      "text/plain",
  ".dtd"          =>      "text/xml",
  ".xml"          =>      "text/xml",
  ".mpeg"         =>      "video/mpeg",
  ".mpg"          =>      "video/mpeg",
  ".mov"          =>      "video/quicktime",
  ".qt"           =>      "video/quicktime",
  ".avi"          =>      "video/x-msvideo",
  ".asf"          =>      "video/x-ms-asf",
  ".asx"          =>      "video/x-ms-asf",
  ".wmv"          =>      "video/x-ms-wmv",
  ".bz2"          =>      "application/x-bzip",
  ".tbz"          =>      "application/x-bzip-compressed-tar",
  ".tar.bz2"      =>      "application/x-bzip-compressed-tar"
 )

url.access-deny             = ( "~", ".inc" )
server.port                = 2080

fastcgi.server             = ( "prog1" => 
                                ("prog1" =>("socket" => "/tmp/prog1.socket")),
                               "prog2" =>
                                ("prog2" =>("socket" => "/tmp/prog2.socket"))
                            )

这样lighttpd将监听于2088端口，访问http://highload.xxx.com:2088/prog1或prog2就可以执行fastcgi应用了。

注意，由于prog1/prog2等程序是非PHP 的fastcgi程序，由perl/c写成，因此必须用lighttpd的spawn-fcgi程序实现将这些fcgi应用运行，才能启动lighttpd，否则lighttpd会出错。

进入/usr/local/lighttpd/bin，执行：
./spawn-fcgi -s /tmp/prog1.socket -f /var/www/vhost/highload/prog1

./spawn-fcgi -s /tmp/prog2.socket -f /var/www/vhost/highload/prog2

执行成功的话，将显示：

spawn-fcgi.c.160: child spawned successfully: PID: 602

重新启动apache，这样凡是访问http://highload.xxx.com/fcgi-bin/prog1或prog2，将自动定向到http://highload.xxx.com:2080/prog*。

经过这样改进后，平均的Apache进程数从650-700降低到250，其余的400-500个并发就由lighttpd来处理。整机的负载也降低了很多。主要是内存使用大幅度降低了。只有原来的40%用量，swap余量非常足够:-)

而且最重要的是，响应速度快了很多。以下是并发请求的监视图：

注意：图上显示的是按每秒的并发请求次数，而不是并发连接数，并发连接数大概是这个数的10倍，也即如果有25请求/秒，那么实际在一段时间内的持续并发连接数就有250-300个。