Apache压力工具ab介绍

崬城衞

　　关键字： 压力测试 ,ab ,apache
转自：http://www.rickyzhu.com/129_quick-introduce-to-ab.html
Apache压力测试工具apache bench 简称ab.主要是从系统设计和开发的角度去评价系统在一定压力下的表现,就正如下面的介绍一样,看每秒系统能支持的并发请求.从而进行相关的调优操作. 下面是ab的官方介绍.
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol (HTTP) server. It is designed to give you an impression of how your current Apache installation performs. This especially shows you how many requests per second your Apache installation is capable of serving.
支持的参数和参数的介绍如下:
ab [ -A auth-username:password ] [ -c concurrency ] [ -C cookie-name=value ] [ -d ] [ -e csv-file ] [ -ggnuplot-file ] [ -h ] [ -H custom-header ] [ -i ] [ -k ] [ -n requests ] [ -p POST-file ] [ -P proxy-auth-username:password ] [ -q ] [ -s ] [ -S ] [ -t timelimit ] [ -T content-type ] [ -v verbosity] [ -V ] [ -w ] [ -x
-attributes ] [ -X proxy[:port] ] [ -y  -attributes  ] [ -z 

[tr][td]-attributes ] [http://]hostname[:port]/path

-A auth-username:passwordSupply 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 concurrencyNumber of multiple requests to perform at a time. Default is one request at a time.-C cookie-name=valueAdd a Cookie: line to the request. The argument is typically in the form of a name=value pair. This field is repeatable.-dDo not display the “percentage served within XX [ms] table”. (legacy support).-e csv-fileWrite 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-fileWrite 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.-hDisplay usage information.-H custom-headerAppend 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").-iDo HEAD requests instead of GET.-kEnable the HTTP KeepAlive feature, i.e., perform multiple requests within one HTTP session. Default is no KeepAlive.-n requestsNumber 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-fileFile containing data to POST.-P proxy-auth-username:passwordSupply 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).-qWhen 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.-sWhen 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.-SDo 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 timelimitMaximum 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-typeContent-type header to use for POST data.-v verbositySet 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.-VDisplay version number and exit.-wPrint out results in HTML tables. Default table is two columns wide, with a white background.-x  -attributesString to use as attributes for  . Attributes are inserted  here >.-X proxy[:port]Use a proxy server for the requests.-y  -attributesString to use as attributes for  .

-z -attributesString to use as attributes for 

.

下面是一个具体的例子：
在命令行下输出：
./ab -n number_of_total_requests -c number_of_simultaneous_requestshttp://your_web_server/your_php_app.php
 
例如：./ab -n 1000 -c 50 http://www.domain.com/myapp.php
AB将同时向http://www.domain.com/myapp.php发出50个并发请求，共发出1000次。
 
 
测试结果将可能是这样的：
Server Software: Apache/2.0.16
Server Hostname: localhost
Server Port: 80
Document Path: /myapp.php
Document Length: 1311 bytes
Concurrency Level: 50
Time taken for tests: 8.794 seconds
Complete requests: 1000
Failed requests: 0
Total transferred: 1754000 bytes
HTML transferred: 1311000 bytes
Requests per second: 113.71
Transfer rate: 199.45 kb/s received
Connection Times (ms)
min avg max
Connect: 0 0 5
Processing: 111 427 550
Total: 111 427 555
myapp.php每秒钟可以处理的请求数为113.71个。将请求数增加，看看服务器能否处理更大的压力。你也需要调节Apache的 MaxClients,ThreadsPerChild,MaxThreadsPerChild等参数，基于你的httpd.conf中的MPM模块选择。
如果你想得到更详细的信息，请到www.apache.org上查阅一些更深入的文档，包括模块和第三方的提高效率的工具。修改httpd.conf后，要重启Apache服务器，然后再用AB测试。你会看到每秒请求数增加或减少。记下每次的参数，最后选择最佳效率的那种配置。