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
