ab 的全稱是 ApacheBench ， 是 Apache 附帶的一個小工具 ， 專門用於 HTTP Server 的 benchmark testing ， 可以同時模擬多個併發請求。前段時間看到公司的開發人員也在用它作一些測試，看起來也不錯，很簡單，也很容易使用，所以今天花一點時間看了一下。

通過下面的一個簡單的例子和註釋，相信大家可以更容易理解這個工具的使用。

下載地址  http://httpd.apache.org/  選擇你需要的版本
解壓即可  

一個簡單的例子

/* 在這個例子的一開始，我執行了這樣一個命令  這個命令的意思是啟動 ab ，向 www.google.com

C:\Program Files\Apache Software Foundation\Apache2.2\bin>ab -n 10 -c 10 http

://www.google.com/

/* 在這個例子的一開始，我執行了這樣一個命令 ab -n 10 -c 10 http://www.google.com/(不要忘了最後一個'/')。這個命令的意思是啟動 ab ，向 www.google.com 傳送10個請求(-n 10) ，並每次傳送10個請求(-c 10)——也就是說一次都發過去了。跟著下面的是 ab 輸出的測試報告。*/

下面是執行結果 

This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0

Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/

Copyright 1997-2005 The Apache Software Foundation, http://www.apache.org/

Benchmarking www.google.com (be patient).....done

Server Software:        GWS/2.1

Server Hostname:        www.google.com

Server Port:            80

Document Path:          /

Document Length:        230 bytes

Concurrency Level:      10

/* 整個測試持續的時間 * /

Time taken for tests:   3.234651 seconds

/* 完成的請求數量 */

Complete requests:      10

/* 失敗的請求數量 */

Failed requests:        0

Write errors:           0

Non-2xx responses:      10

Keep-Alive requests:    10

/* 整個場景中的網路傳輸量 */

Total transferred:      6020 bytes

/* 整個場景中的 HTML 內容傳輸量 */

HTML transferred:       2300 bytes

/* 大家最關心的指標之一，相當於 LR 中的 每秒事務數 ，後面括號中的 mean 表示這是一個平均值 */

Requests per second:    3.09 [#/sec] (mean)

/* 大家最關心的指標之二，相當於 LR 中的 平均事務響應時間 ，後面括號中的 mean 表示這是一個平均值 */

Time per request:       3234.651 [ms] (mean)

/* 這個還不知道是什麼意思，有知道的朋友請留言，謝謝 ^_^ */

Time per request:       323.465 [ms] (mean, across all concurrent requests)

/* 平均每秒網路上的流量，可以幫助排除是否存在網路流量過大導致響應時間延長的問題 */

Transfer rate:          1.55 [Kbytes/sec] received

/* 網路上消耗的時間的分解，各項資料的具體演算法還不是很清楚 */

Connection Times (ms)

              min  mean[+/-sd] median   max

Connect:       20  318 926.1     30    2954

Processing:    40 2160 1462.0   3034    3154

Waiting:       40 2160 1462.0   3034    3154

Total:         60 2479 1276.4   3064    3184

/* 下面的內容為整個場景中所有請求的響應情況。在場景中每個請求都有一個響應時間，其中 50 ％ 的使用者響應時間小於 3064 毫秒， 60 ％ 的使用者響應時間小於 3094 毫秒，最大的響應時間小於 3184 毫秒 */

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

  50%   3064

  66%   3094

  75%   3124

  80%   3154

  90%   3184

  95%   3184

  98%   3184

  99%   3184

  100%   3184 (longest request)

更多資訊

ab 不像 LR 那麼強大，但是它足夠輕便，如果只是在開發過程中想檢查一下某個模組的響應情況，或者做一些場景比較簡單的測試， ab 還是一個不錯的選擇——至少不用花費很多時間去學習 LR 那些複雜的功能，就更別說那 License 的價格了。

下面是 ab 的詳細引數解釋，大家有興趣的可以研究一下，最近沒有足夠多的時間研究，如果哪位朋友有興趣希望可以幫忙翻譯一下每個引數的含義，有問題討論也歡迎在這裡回帖 ^_^

ab [ - A auth-username : password ] [ - c concurrency ] [ - C cookie-name = value ] [ - d ] [ - ecsv-file ] [ - g gnuplot-file ] [ - h ] [ - H custom-header ] [ - i ] [ - k ] [ - n requests ] [ - pPOST-file ] [ - P proxy-auth-username : password ] [ - q ] [ - s ] [ - S ] [ - t timelimit ] [ - Tcontent-type ] [ - v verbosity ] [ - V ] [ - w ] [ - x <table>-attributes ] [ - X proxy [: port ] ] [ - y<tr>-attributes ] [ - z <td>-attributes ] [http://] hostname [: port ]/ path

-A auth-username : password

Supply BASIC Authentication credentials to the server. The username and password are separated by a single : and sent on the wire base64 encoded. The string is sent regardless of whether the server needs it (i.e. , has sent an 401 authentication needed).

-c concurrency

Number of multiple requests to perform at a time. Default is one request at a time.

-C cookie-name = value

Add a Cookie: line to the request. The argument is typically in the form of a name = value pair. This field is repeatable.

-d

Do not display the "percentage served within XX [ms] table". (legacy support).

-e csv-file

Write a Comma separated value (CSV) file which contains for each percentage (from 1% to 100%) the time (in milliseconds) it took to serve that percentage of the requests. This is usually more useful than the 'gnuplot' file; as the results are already 'binned'.

-g gnuplot-file

Write all measured values out as a 'gnuplot' or TSV (Tab separate values) file. This file can easily be imported into packages like Gnuplot, IDL, Mathematica, Igor or even Excel. The labels are on the first line of the file.

-h

Display usage information.

-H custom-header

Append extra headers to the request. The argument is typically in the form of a valid header line, containing a colon-separated field-value pair (i.e. , "Accept-Encoding: zip/zop;8bit" ).

-i

Do HEAD requests instead of GET .

-k

Enable the HTTP KeepAlive feature, i.e. , perform multiple requests within one HTTP session. Default is no KeepAlive.

-n requests

Number of requests to perform for the benchmarking session. The default is to just perform a single request which usually leads to non-representative benchmarking results.

-p POST-file

File containing data to POST.

-P proxy-auth-username : password

Supply BASIC Authentication credentials to a proxy en-route. The username and password are separated by a single : and sent on the wire base64 encoded. The string is sent regardless of whether the proxy needs it (i.e. , has sent an 407 proxy authentication needed).

-q

When processing more than 150 requests, ab outputs a progress count on stderr every 10% or 100 requests or so. The -q flag will suppress these messages.

-s

When compiled in ( ab -h will show you) use the SSL protected https rather than the http protocol. This feature is experimental and very rudimentary. You probably do not want to use it.

-S

Do not display the median and standard deviation values, nor display the warning/error messages when the average and median are more than one or two times the standard deviation apart. And default to the min/avg/max values. (legacy support).

-t timelimit

Maximum number of seconds to spend for benchmarking. This implies a -n 50000 internally. Use this to benchmark the server within a fixed total amount of time. Per default there is no timelimit.

-T content-type

Content-type header to use for POST data.

-v verbosity

Set verbosity level - 4 and above prints information on headers, 3 and above prints response codes (404, 200, etc.), 2 and above prints warnings and info.

-V

Display version number and exit.

-w

Print out results in HTML tables. Default table is two columns wide, with a white background.

-x <table>-attributes

String to use as attributes for <table> . Attributes are inserted <table here > .

-X proxy [: port ]

Use a proxy server for the requests.

-y <tr>-attributes

String to use as attributes for <tr> .

-z <td>-attributes

String to use as attributes for <td>