引言： ab測試是業界比較流行和簡單易用的一種壓力測試工具包，本文將簡要介紹其核心使用的方法。

1.  ab

  ab是Apache HTTP server benchmarking tool的縮寫，可以用以測試HTTP請求的伺服器效能。其是通過命令列的不同引數從而提供簡單易用的效能測試工具命令組合。

2.   環境資訊

    CentOS 7,  ab的版本是2.3， 目前最新的版本是2.4

   

3.  使用指南

   3.1  檢視幫助檔案內容

[[email protected]~]# ab -h
Usage: ab [options] [http[s]://]hostname[:port]/path
Options are:
    -n requests     Number of requests to perform
    -c concurrency  Number of multiple requests to make at a time
    -t timelimit    Seconds to max. to spend on benchmarking
                    This implies -n 50000
    -s timeout      Seconds to max. wait for each response
                    Default is 30 seconds
    -b windowsize   Size of TCP send/receive buffer, in bytes
    -B address      Address to bind to when making outgoing connections
    -p postfile     File containing data to POST. Remember also to set -T
    -u putfile      File containing data to PUT. Remember also to set -T
    -T content-type Content-type header to use for POST/PUT data, eg.
                    'application/x-www-form-urlencoded'
                    Default is 'text/plain'
    -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.
    -q              Do not show progress when doing more than 150 requests
    -g filename     Output collected data to gnuplot format file.
    -e filename     Output CSV file with percentages served
    -r              Don't exit on socket receive errors.
    -h              Display usage information (this message)
    -Z ciphersuite  Specify SSL/TLS cipher suite (See openssl ciphers)
    -f protocol     Specify SSL/TLS protocol
                    (SSL2, SSL3, TLS1, TLS1.1, TLS1.2 or ALL)
 

 3.2  初步測試

     引數說明： -n 請求數量， -c 併發數量    

      ab  option  url-address

      Case  1:      ab -n1000 -c10 http://www.baidu.com/index.html

      結果資訊如下：

[[email protected] ~]# ab -n1000 -c10 http://www.baidu.com/index.html
This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.baidu.com (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
apr_socket_recv: Connection reset by peer (104)
 

      分析百度不允許直接這麼測試，直接將請求重置。

    Case 2:  

   command:  ab -n1000 -c10 http://www.csdn.net/index.html

      測試結果：

[[email protected]~]# ab -n1000 -c10 http://www.csdn.net/index.html
This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.csdn.net (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
Completed 1000 requests
Finished 1000 requests

//伺服器資訊： openresty
Server Software:        openresty
Server Hostname:        www.csdn.net
Server Port:            80

Document Path:          /index.html
Document Length:        100686 bytes

Concurrency Level:      10
Time taken for tests:   24.567 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      100982000 bytes
HTML transferred:       100686000 bytes
//伺服器的吞吐量，每秒請求處理量
Requests per second:    40.71 [#/sec] (mean)
//使用者平均等待時間
Time per request:       245.665 [ms] (mean)
//伺服器端單個請求的處理時間
Time per request:       24.567 [ms] (mean, across all concurrent requests)
Transfer rate:          4014.21 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:       38   71 175.3     44    3065
Processing:   114  173  30.4    170     446
Waiting:       38   46   9.6     44     302
Total:        152  244 180.7    213    3294

Percentage of the requests served within a certain time (ms)
  50%    213
  66%    238
  75%    247
  80%    249
  90%    256
  95%    288
  98%   1201
  99%   1248
 100%   3294 (longest request)
 

  測試結果： 請求吞吐量為：40.71/s,  單個請求處理時間為：24.567

  Case 2:   ab -n1000 -c10  http://www.sina.com.cn/index.html

[[email protected]~]# ab -n1000 -c10 http://www.sina.com.cn/index.html
This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking www.sina.com.cn (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
Completed 1000 requests
Finished 1000 requests

//後臺伺服器是nginx
Server Software:        nginx
Server Hostname:        www.sina.com.cn
Server Port:            80

Document Path:          /index.html
Document Length:        27201 bytes

Concurrency Level:      10
Time taken for tests:   8.470 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      27538766 bytes
HTML transferred:       27201000 bytes
Requests per second:    118.06 [#/sec] (mean)
Time per request:       84.704 [ms] (mean)
Time per request:       8.470 [ms] (mean, across all concurrent requests)
Transfer rate:          3174.97 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:       15   27  70.7     21    1026
Processing:    32   57  24.3     53     321
Waiting:       15   24  16.4     22     253
Total:         47   84  74.9     74    1094

Percentage of the requests served within a certain time (ms)
  50%     74
  66%     84
  75%     90
  80%     92
  90%    103
  95%    120
  98%    124
  99%    289
 100%   1094 (longest request)

分析結果： 請求吞吐量為：118.06/s,  伺服器處理單個請求的時間為8.470 ms。 相比csdn.net而言，舒淇效率將近3倍。csdn為40個請求/s, 單個請求為24ms。

那提個問題為什麼sina比csdn的效能高3倍呢？ 我們來簡要分析一下，首先是傳輸的資料量，csdn是sina的3倍；以下皆以mean時間為準。

站點	connect	processing	waiting	total
csdn	71	173	46	244
sina.com.cn	27ms	57	24	84

   整體而言，可以發現sina.com.cn在各個節點上都是由於csdn的效能的。

3.3  加大併發數的壓測（單臺機器）

      case 1: ab -c100 -n1000 http://www.csdn.net/index.html   [100併發數]

HTML transferred:       100580778 bytes
Requests per second:    52.39 [#/sec] (mean)
Time per request:       1908.606 [ms] (mean)
Time per request:       19.086 [ms] (mean, across all concurrent requests)
Transfer rate:          5161.49 [Kbytes/sec] received

  相比之前的資料，併發設為100之後，吞吐量從40上升到52， 單個請求響應時間從24ms降低為19ms

    case 2:  ab -c200 -n1000 http://www.csdn.net/index.html

HTML transferred:       100358484 bytes
Requests per second:    48.32 [#/sec] (mean)
Time per request:       4139.429 [ms] (mean)
Time per request:       20.697 [ms] (mean, across all concurrent requests)
Transfer rate:          4749.23 [Kbytes/sec] received

   相比之前的資料，併發數為200， 吞吐量下降了，響應時間變長。

    case 3: ab -c500 -n1000 http://www.csdn.net/index.html   [100併發數]

HTML transferred:       83827148 bytes
Requests per second:    49.05 [#/sec] (mean)
Time per request:       10193.544 [ms] (mean)
Time per request:       20.387 [ms] (mean, across all concurrent requests)
Transfer rate:          4029.59 [Kbytes/sec] received

   結果分析： 整體資料無太大變化，只是對於單個使用者而言，等待時間變得比較久，需要10s.

6. 參考資料

•  http://httpd.apache.org/docs/current/programs/ab.html