ab命令

一、ab的原理

ab是apachebench命令的缩写。

ab的原理：ab命令会创建多个并发访问线程，模拟多个访问者同时对某一URL地址进行访问。它的测试目标是基于URL的，因此，它既可以用来测试apache的负载压力，也可以测试nginx、lighthttp、tomcat、IIS等其它Web服务器的压力。

ab命令对发出负载的计算机要求很低，它既不会占用很高CPU，也不会占用很多内存。但却会给目标服务器造成巨大的负载，其原理类似CC攻击。自己测试使用也需要注意，否则一次上太多的负载。可能造成目标服务器资源耗完，严重时甚至导致死机。

二、ab的安装

yum -y install httpd-tools
ab -V

三、ab参数说明

[root@myhost vhost]# ab --help
ab: wrong number of arguments
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
                    (SSL3, TLS1, TLS1.1, TLS1.2 or ALL)

四、ab实际使用

ab的命令参数比较多，我们经常使用的是-c和-n参数。

[root@myhost vhost]# ab -c 10000 -n 100000 http://www.baidu.com
-c表示并发用户数
-n表示请求总数

五、输出结果

Server Software:        nginx
Server Hostname:        127.0.0.1
Server Port:            80

Document Path:          /wordpress
Document Length:        178 bytes   #请求大小

Concurrency Level:      10000       #并发请求量
Time taken for tests:   7.926 seconds    #整个测试持续时间
Complete requests:      100000          #完成的请求数
Failed requests:        0               #失败的请求数
Write errors:           0
Non-2xx responses:      100000
Total transferred:      36800000 bytes    #整个场景中网络传输量
HTML transferred:       17800000 bytes    #整个场景中的HTML内容传输量
Requests per second:    12615.91 [#/sec] (mean)  #吞吐速率，大家最关心的指标之一
Time per request:       792.650 [ms] (mean)    #用户平均请求等待时间，大家最关心的指标之二
Time per request:       0.079 [ms] (mean, across all concurrent requests)  #服务器平均请求处理的时间，大家最关心的指标之三
Transfer rate:          4533.84 [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:        0  510 1056.6      3    7026
Processing:     3   28  89.9      8    1889
Waiting:        0   25  89.4      6    1887
Total:          7  538 1079.8     12    7240

Percentage of the requests served within a certain time (ms)
  50%     12
  66%     22
  75%   1016
  80%   1022
  90%   1231
  95%   3027
  98%   3232
  99%   3828
 100%   7240 (longest request)

定时任务例子

#* * * * * /usr/bin/ab -r -c 10000 -n 100000 http://192.168.223.143:8317/hdpanel/login

最后

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