简单模拟一下ab压力测试

简单了解下ab

ab全程是apache benchmark，是apache官方推出的一个工具，创建多个并发访问线程，模拟多个访问者同时对一个URL地址进行访问。它的测试目标是基于URL的，因此它既可以来测试apache的负载压力，也可以测试Nginx等服务器的压力。

ab压力测试需要注意哪些？

测试的注意事项：
测试机器与被测试机器要分开，别在同一台机器上测试，否则结果是不准确的
不要对线上的服务器做测试，否则挂了就不好了哦。
观察测试工具ab所在的机器，以及被测试的前端机器的CPU，内存，网络等都不超过最高限度的75%。

下面测试下，两台服务器。

192.168.136.135 作为被测试的WEB服务器

192.168.136.148 作为ab测试的服务器

首先确保ab测试服务器安装ab，使用以下命令yum安装

yum install -y ab  //安装

安装完成之后，执行ab命令，返回一些帮助信息，确保安装成功



访问以下被测试的服务器，确保正常



执行下面的命令进行测试

ab -c 100 -n 5000 http://192.168.136.135/phpinfo.php      //模拟100个并发数，总共访问5000次

返回的结果

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 192.168.136.135 (be patient)
Completed 500 requests
Completed 1000 requests
Completed 1500 requests
Completed 2000 requests
Completed 2500 requests
Completed 3000 requests
Completed 3500 requests
Completed 4000 requests
Completed 4500 requests
Completed 5000 requests
Finished 5000 requests

Server Software:        nginx     //被测试的服务器是Nginx
Server Hostname:        192.168.136.135   //Hostname
Server Port:            80                          //端口

Document Path:          /phpinfo.php        //path
Document Length:        96660 bytes     //文档大小

Concurrency Level:      100                   //100个并发
Time taken for tests:   11.860 seconds   //时间花费
Complete requests:      5000                //请求了5000次
Failed requests:        486                   //失败了486次
(Connect: 0, Receive: 0, Length: 486, Exceptions: 0)
Write errors:           0
Total transferred:      484274801 bytes
HTML transferred:       483509342 bytes
Requests per second:    421.60 [#/sec] (mean)   //QPS值，不高
Time per request:       237.194 [ms] (mean)
Time per request:       2.372 [ms] (mean, across all concurrent requests)
Transfer rate:          39876.53 [Kbytes/sec] received

Connection Times (ms)
min  mean[+/-sd] median   max
Connect:        0    1   1.3      1      13
Processing:    45  234  44.2    231     540
Waiting:       23  187  40.7    182     442
Total:         47  235  44.0    232     540

Percentage of the requests served within a certain time (ms)
50%    232     //平均页面的响应时间是232毫秒
66%    238
75%    243
80%    247
90%    280
95%    302
98%    382
99%    442
100%    540 (longest request)  //最长是540毫秒

把并发数改为50测试一下

ab -c 50 -n 5000 http://192.168.136.135/phpinfo.php[/code] 
.....
Connection Times (ms)
min  mean[+/-sd] median   max
Connect:        0    1   1.3      1      18
Processing:    52  104  13.2    104     158
Waiting:       36   79   8.1     79     135
Total:         65  105  13.3    104     170

Percentage of the requests served within a certain time (ms)
50%    104
66%    108
75%    111
80%    114
90%    126
95%    131
98%    135
99%    139
100%    170 (longest request)
[root@localhost ~]# ab -c 50 -n 5000 http://192.168.136.135/phpinfo.php 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 192.168.136.135 (be patient)
Completed 500 requests
Completed 1000 requests
Completed 1500 requests
Completed 2000 requests
Completed 2500 requests
Completed 3000 requests
Completed 3500 requests
Completed 4000 requests
Completed 4500 requests
Completed 5000 requests
Finished 5000 requests

Server Software:        nginx
Server Hostname:        192.168.136.135
Server Port:            80

Document Path:          /phpinfo.php
Document Length:        96660 bytes

Concurrency Level:      50
Time taken for tests:   10.987 seconds
Complete requests:      5000
Failed requests:        478
(Connect: 0, Receive: 0, Length: 478, Exceptions: 0)
Write errors:           0
Total transferred:      484064467 bytes
HTML transferred:       483299467 bytes
Requests per second:    455.07 [#/sec] (mean)  //QPS
Time per request:       109.874 [ms] (mean)
Time per request:       2.197 [ms] (mean, across all concurrent requests)
Transfer rate:          43023.80 [Kbytes/sec] received

Connection Times (ms)
min  mean[+/-sd] median   max
Connect:        0    1   0.9      1      14
Processing:    32  109  14.4    108     192
Waiting:        9   82  10.1     83     158
Total:         32  109  14.3    109     193

Percentage of the requests served within a certain time (ms)
50%    109
66%    112
75%    115
80%    118
90%    129
95%    136
98%    144
99%    152
100%    193 (longest request)  //最长193


测试结果其实并不实际很准确，因为测试机和被测试机都在一台机器上。这里值是了解。

然后再来一个静态的html测试下



ab -c 100 -n 5000 http://192.168.136.135/ab.html[/code] 
很快完成测试

Server Software:        nginx
Server Hostname:        192.168.136.135
Server Port:            80

Document Path:          /ab.html
Document Length:        23 bytes

Concurrency Level:      100
Time taken for tests:   0.830 seconds
Complete requests:      5000
Failed requests:        0  //0次失败
Write errors:           0
Total transferred:      1241916 bytes
HTML transferred:       115644 bytes
Requests per second:    6024.71 [#/sec] (mean)  //QPS达到了6000+
Time per request:       16.598 [ms] (mean)
Time per request:       0.166 [ms] (mean, across all concurrent requests)
Transfer rate:          1461.36 [Kbytes/sec] received

Connection Times (ms)
min  mean[+/-sd] median   max
Connect:        1    7   1.4      7      23
Processing:     5    9   1.6      9      24
Waiting:        0    7   1.5      7      11
Total:         10   16   1.8     16      29

Percentage of the requests served within a certain time (ms)
50%     16  //响应也很快
66%     17
75%     17
80%     17
90%     18
95%     19
98%     20
99%     23
100%     29 (longest request)


所以静态和动态的对比，不但要考虑到服务器的性能，还要考虑到程序的优化。