4. FastCGI 有多快？
看完安装 FastCGI 的阿帕契模块，以及无聊的程序设计注意事项后，我们来看看一些可以让人振奋精神的数据，效能比较 (bench mark) 总是计算机玩家的最爱 :-)
4.1 评比工具 - ApacheBench
在阿帕契服务器的套件中，有一个叫做 ab (ApacheBench) 的工具。ApacheBench 主要是用来测试阿帕契服务器执行效率用的，我们就以 ApacheBench 做为 CGI vs. FastCGI 的评比工具。
ApacheBench 可以针对某个特定的 URL 仿真出连续的联机请求，同时还可以仿真出同时间点数个相同的联机请求，因此利用 ApacheBench 可帮助我们在网站开发期间仿真实际上线可能的情况，利用仿真出来的数据做为调整服务器设定或程序的依据。 ApacheBench 的用法如下：
Usage: /usr/local/apache/bin/ab [options] [http://]hostname[:port]/path
Options are:
-n requests Number of requests to perform
-c concurrency Number of multiple requests to make
-t timelimit Seconds to max. wait for responses
-p postfile File containg data to POST
-T content-type Content-type header for POSTing
-v verbosity How much troubleshooting info to print
-w Print out results in HTML tables
-x attributes String to insert as table attributes
-y attributes String to insert as tr attributes
-z attributes String to insert as td or th attributes
-V Print version number and exit
-k Use HTTP KeepAlive feature
-h Display usage information (this message)
假设我们要对 echo.fcg 做测试，仿真 1000 次的联机请求，而且同一时间有 20 个并行的 (concurrent) 联机请求的情况，只要在命令列模式下执行
$ ab -n 1000 -c 20 http://localhost/fcgi-bin/echo.fcg
稍等一会，ApacheBench 会把结果秀出来，
This is ApacheBench, Version 1.3
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-1999 The Apache Group, http://www.apache.org/
Benchmarking localhost (be patient)... Server Software: Apache/1.3.6
Server Hostname: localhost
Server Port: 80
Document Path: /fcgi-bin/echo.fcg
Document Length: 995 bytes
Concurrency Level: 20
Time taken for tests: 6.859 seconds
Complete requests: 1000
Failed requests: 0
Total transferred: 1142000 bytes
HTML transferred: 995000 bytes
Requests per second: 145.79
Transfer rate: 166.50 kb/s received
