JMeter比较适合做性能测试（模拟用户各种请求设置并发数，发起请求），而AB程序更适合做基准或者压力测试，来测试服务能扛住的最大压力。
AB安装方式很简单，在Centos下，使用
[root@centos02 conf]# yum intall -y httpd-tools
输入ab -help，可以看到可用的参数
[root@centos02 conf]# ab -help 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 -t timelimit Seconds to max. wait for responses -b windowsize Size of TCP send/receive buffer, in bytes -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 for POSTing, 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. -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, or ALL)
比较常用的是 -k 使用 keepalive默认是禁止的，-c 并发数，-n 总请求次数
简单示例
[root@centos02 conf]# ab -k -c 1 -n 2 http://www.baidu.com/index.html This is ApacheBench, Version 2.3 <$Revision: 655654 $> 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).....done Server Software: BWS/1.1 Server Hostname: www.baidu.com Server Port: 80 Document Path: /index.html Document Length: 111309 bytes Concurrency Level: 1 Time taken for tests: 2.573 seconds Complete requests: 2 Failed requests: 1 (Connect: 0, Receive: 0, Length: 1, Exceptions: 0) Write errors: 0 Keep-Alive requests: 0 Total transferred: 225033 bytes HTML transferred: 223139 bytes Requests per second: 0.78 [#/sec] (mean) Time per request: 1286.352 [ms] (mean) Time per request: 1286.352 [ms] (mean, across all concurrent requests) Transfer rate: 85.42 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 24 28 5.1 32 32 Processing: 1210 1251 57.6 1292 1292 Waiting: 283 292 12.9 301 301 Total: 1242 1279 52.6 1316 1316 Percentage of the requests served within a certain time (ms) 50% 1316 66% 1316 75% 1316 80% 1316 90% 1316 95% 1316 98% 1316 99% 1316 100% 1316 (longest request)
测试前，需要关闭一个系统参数，避免系统认为是攻击行为
[root@centos02 etc]# vi sysctl.conf
net.ipv4.tcp_syncookies = 0
另外请求带上 -r 可以保证在个别请求错误时，不退出。
不做这2个配置，可能会出现 apr_poll: The timeout specified has expired (70007)或者apr_socket_recv: Connection reset by peer (104)的错误
完整例子如
[root@centos02 bin]# ab -k -r -c 1000 -n 100000 http://www.shop.com/brand/content/1.jhtml
1000个并发下，请求100000次
