Web性能压力测试工具ApacheBench(ab)

ApacheBench是apache自带的ab程序，可以实现对Apache或其他web服务器的性能压力测试。

ab会并发创建很多个现成来模拟多个用户同时对url进行访问。ab命令对发出负载的计算机要求很低，既不会占用很高CPU，也不会占用很多内存，但却会给目标服务器造成巨大的负载。

常用的命令格式举例：

ab -n 5000 -c 1000 url

-n后面的4000代表总共发出4000个请求；-c后面的1000表示采用1000个并发（模拟1000个人同时访问），后面的网址表示测试的目标URL。

执行结果：

07:29 [root@IP]$ ab -n 2000 -c 100 http://www.xxx.com/a/id_XMTM5NDY0.html
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking ding.youku.com (be patient)
Completed 200 requests
Completed 400 requests
Completed 600 requests
Completed 800 requests
Completed 1000 requests
Completed 1200 requests
Completed 1400 requests
Completed 1600 requests
Completed 1800 requests
Completed 2000 requests
Finished 2000 requests


Server Software: nginx
Server Hostname: ding.youku.com
Server Port: 80

Document Path: /a/id_XMTM5NDY0.html
Document Length: 17412 bytes

Concurrency Level: 100
Time taken for tests: 2.268 seconds
Complete requests: 2000
Failed requests: 2
(Connect: 0, Receive: 0, Length: 2, Exceptions: 0)
Write errors: 0
Non-2xx responses: 2
Total transferred: 35543234 bytes
HTML transferred: 34817778 bytes
Requests per second: 881.67 [#/sec] (mean)
Time per request: 113.421 [ms] (mean)            concurrency *timetaken * 1000 / done
Time per request: 1.134 [ms] (mean, across all concurrent requests)    timetaken * 1000 / done
Transfer rate: 15301.47 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 2 4 2.9 3 21
Processing: 25 70 184.8 30 2050
Waiting: 22 38 82.4 25 1225
Total: 27 74 186.3 32 2070

Percentage of the requests served within a certain time (ms)
50% 32
66% 34
75% 35
80% 37
90% 42
95% 267
98% 781
99% 1182
100% 2070 (longest request)