1 概述
ab（ApacheBench）是Apache自带的超文本传输协议(HTTP)性能测试工具。 其设计意图是描绘当前所安装的Apache的执行性能， 主要是显示你安装的Apache每秒可以处理多少个请求。
2 使用
2.1 安装
Apache服务器套件自带ab，只要安装Apache即可，无需另行安装ab。ab位于%ApacheHome%/bin目录下（“%ApacheHome%”为Aapche安装路径），你也可以把ab.exe文件copy出来，独立使用。
2.2 参数列表
C:\>ab
ab: wrong number of arguments
Usage: 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 containing 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
-i Use HEAD instead of GET
-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
-C attribute Add cookie, eg. 'Apache=1234. (repeatable)
-H attribute Add Arbitrary header line, eg. 'Accept-Encoding: gzip'
Inserted after all normal header lines. (repeatable)
-A attribute Add Basic WWW Authentication, the attributes
are a colon separated username and password.
-P attribute Add Basic Proxy Authentication, the attributes
are a colon separated username and password.
-X proxy:port Proxyserver and port number to use
-V Print version number and exit
-k Use HTTP KeepAlive feature
-d Do not show percentiles served table.
-S Do not show confidence estimators and warnings.
-g filename Output collected data to gnuplot format file.
-e filename Output CSV file with percentages served
-h Display usage information (this message)
* 中文的列表可以查看Apache手册中文版。
以上参数最常用的是-n 在测试会话中所执行的请求个数；和-c 一次同时产生的并发请求个数。
2.3 实例
假设我们要测试一个PHP论坛系统，其中一个性能测试用例是：“同时处理50个并发请求并运行 1000 次index.php 首页”，我们可以在cmd shell中输入 ab -n 1000 -c 50 http://172.16.11.180:88/bbs/index.php，运行结束后，ab会自动显示测试结果，如下：
E:\Webser\Apache2\bin>ab -n 1000 -c 50 http://172.16.11.180:88/bbs/index.php
This is ApacheBench, Version 2.0.41-dev <$Revision: 1.121.2.12 $> apache-2.0
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-2002 The Apache Software Foundation, http://www.apache.org/
Benchmarking 172.16.11.180 (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Finished 1000 requests
Server Software: Apache
Server Hostname: 172.16.11.180
Server Port: 88
Document Path: /bbs/index.php
Document Length: 36962 bytes
Concurrency Level: 50
Time taken for tests: 262.515625 seconds
Complete requests: 1000
Failed requests: 198
(Connect: 0, Length: 198, Exceptions: 0)
Write errors: 0
Total transferred: 37408432 bytes
HTML transferred: 36967364 bytes
Requests per second: 3.81 [#/sec] (mean)
Time per request: 13125.781 [ms] (mean)
Time per request: 262.516 [ms] (mean, across all concurrent requests)
Transfer rate: 139.16 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 4.5 0 15
Processing: 297 12818 2427.6 12921 30578
Waiting: 281 12801 2427.6 12906 30562
Total: 312 12820 2427.5 12921 30578
Percentage of the requests served within a certain time (ms)
50% 12921
66% 13203
75% 13453
80% 13546
90% 13781
95% 14156
98% 14750
99% 18328
100% 30578 (longest request)
以上结果指出，在并发50个请求的情况下，完成1000次的访问请求，共花了262.515秒，这个程序每秒可处理3.81个请求。
2.4 问题
在实际使用中，我发现-c 参数，即一次同时产生的并发请求个数最多设置成64，大于等于65就会报错，不知道为什么。
3 资料
ab官方网站：http://httpd.apache.org/docs/2.0/programs/ab.html
Apache 2.0手册中文版翻译项目ab部分：https://support.iap.ac.cn/net/ApacheManual/zh-cn/programs/ab.html
