服务器负载太大而影响程序效率也是很常见的，Apache服务器自带有一个叫AB(ApacheBench)的工具，在bin目录下。使用这个轻巧的工具我们可以对服务器进行负载测试，

基本用法:

ab -n 全部请求数 -c 并发数 测试url

例:ab -n 1000 -c 50 http://www.abc.com/a.php

得到结果类似于(后面颜色字为中文翻译):

Server Software: Apache/2.0.55 Server Hostname: localhost Server Port: 80

Document Path: /1.php Document Length: 82522 bytes #请求文档大小

Concurrency Level: 50 #并发数
Time taken for tests: 92.76140 seconds #全部请求完成耗时 Complete requests: 10000 #全部请求数 Failed requests: 1974 #失败的请求 (Connect: 0, Length: 1974, Exceptions: 0) Write errors: 0 Total transferred: 827019400 bytes #总传输大小 HTML transferred: 825219400 bytes Requests per second: 108.61 [#/sec] (mean) #每秒请求数(平均) Time per request: 460.381 [ms] (mean) #每次并发请求时间(所有并发) Time per request: 9.208 [ms] (mean, across all concurrent requests) #每一请求时间(并发平均)
Transfer rate: 8771.39 [Kbytes/sec] received #传输速率

Connection Times (ms) #连接时间 min mean[+/-sd] median max Connect(#连接): 0 0 2.1 0 46 Processing(#处理): 31 458 94.7 438 1078 Waiting(#等待): 15 437 87.5 422 938 Total: 31 458 94.7 438 1078

其它参数:

-n requests 全部请求数 -c concurrency 并发数 -t timelimit 最传等待回应时间 -p postfile POST数据文件 -T content-type POST Content-type -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 加入cookie, eg. ‘Apache=1234. (repeatable) -H attribute 加入http头, eg. ‘Accept-Encoding: gzip’ Inserted after all normal header lines. (repeatable) -A attribute http验证,分隔传递用户名及密码 -P attribute Add Basic Proxy Authentication, the attributes are a colon separated username and password. -X proxy:port 代理服务器 -V 查看ab版本 -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 -h Display usage information (this message)