apache自带压力测试工具ab的使用及解析

当你搭建了apache服务器并在上面部署了web网站，在网站运行前，为了使apache服务器的性能得到更好的应用，我们可以先对其进行压力测试。进行压力测试其实非常简单，我们也不用再额外下载安装什么测试工具，因为Apache HTTP Server自带了一个压力测试工具——ab，ab的可选参数比较多，但一般我们测试只需要使用其中的两个即可

-n　　即requests，用于指定压力测试总共的执行次数。

-c　　即concurrency，用于指定压力测试的并发数。

在命令行执行命令：

[root@RS1 ~]# ab -n  -c  http://192.168.0.162/index.html
This is ApacheBench, Version 2.3 <$Revision:  $>
Copyright  Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 192.168.0.162 (be patient)
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Completed  requests
Finished  requests

Server Software:        Apache    (服务器软件名称及版本信息)
Server Hostname:        192.168.0.162    (服务器主机名)
Server Port:                (服务器端口)

Document Path:          /index.html    (供测试的URL相对路径)
Document Length:         bytes    (供测试的URL返回的文档大小)

Concurrency Level:          (测试并发数)
Time taken for tests:   1.469 seconds    (压力测试消耗的总时间)
Complete requests:          (完成请求的总次数)
Failed requests:            (失败的请求数)
Write errors:               (网络连接写入错误数)
Total transferred:       bytes    (传输的总数据量)
HTML transferred:        bytes    (HTML文档的总数据量)
Requests per second:    2722.46 [#/sec] (mean)    (平均每秒的请求数)吞吐速率
Time per request:       183.657 [ms] (mean)    (所有并发用户(这里是500)都请求一次的平均时间)用户平均请求等待时间
Time per request:       0.367 [ms] (mean, across all concurrent requests)    (单个用户请求一次的平均时间)服务器平均请求处理的时间
Transfer rate:          982.02 [Kbytes/sec] received    (平均每秒网络上的流量，可以帮助排除是否有存在网络流量过大导致响应时间延长的问题)

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:            152.9
Processing:         266.9
Waiting:            266.9
Total:            305.2         

Percentage of the requests served within a certain time (ms)
  %
  %
  %
  %
  %
  %
  %
  %
 %    (longest request)

以上结果可以看出，服务器压力很小，下面测试一个压力大的

Server Software:        Apache
Server Hostname:        192.168.0.162
Server Port:            

Document Path:          /index.html
Document Length:         bytes

Concurrency Level:
Time taken for tests:   3.257 seconds
Complete requests:
Failed requests:
Write errors:
Total transferred:       bytes
HTML transferred:        bytes
Requests per second:    3070.65 [#/sec] (mean)
Time per request:       1302.655 [ms] (mean)      可以看出用户平均等待时间明显增加
Time per request:       0.326 [ms] (mean, across all concurrent requests)
Transfer rate:          1124.33 [Kbytes/sec] received

在加大并发数，会发现：

[root@RS1 ~]# ab -n  -c  http://192.168.0.162/index.html
This is ApacheBench, Version 2.3 <$Revision:  $>
Copyright  Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 192.168.0.162 (be patient)
Completed  requests
Completed  requests
Completed  requests
apr_socket_recv: Connection reset by peer ()
Total of  requests completed　　（只完成了3W多个请求就断了）

注意：在上面的压力测试中，Apache使用的是默认配置，并没有经过任何优化措施处理。实际上，Apache在经过配置优化后，只要服务器硬件够用，Apache服务器是能够撑起更多的并发量的。