系统环境：
OS:Ubuntu 10.10 (2G)
Servlet Container:tomcat-tomcat-7.0.23 (最大内存：default 256M maxThreads:500)
Web server: apache2.2 (maxClient:250)
设置apache最大连接数
Java代码 
- 在/usr/local/etc/apache22/httpd.conf中加载MPM配置（去掉前面的注释）：
- # Server-pool management (MPM specific)
- Include etc/apache22/extra/httpd-mpm.conf
- 修改d-mpm.conf中对应module如下
- <IfModule mpm_prefork_module>
- StartServers 5
- MinSpareServers 5
- MaxSpareServers 10
- ServerLimit 3000
- MaxClients 2000
- MaxRequestsPerChild 0
- </IfModule>]
一、benchmark测试方法
./ab -n 100000 -c 100 http://localhost/test
使用ab进行测试，当并发较高时，会出现以下错误
错误1：apr_socket_recv: Connection reset by peer (104)
Java代码
- apache2.2及以下版本
- 修改support下面的ab.c源代码， 大概在
- line 1369， 修改成
- 1368 return;
- 1369 } else {
- 1370 //apr_err("apr_socket_recv", status);
- 1371 bad++;
- 1372 close_connection(c);
- 1373 return;
- 1374 }
- 然后编译安装
错误2：Too many open files (24)
(PS；使用AJP协议和HTTP协议，多次进行测试，取测试结果较好的一次进行比较)
二、使用AJP后的benchmark
Java代码
- Benchmarking localhost (be patient)
- Completed 10000 requests
- Completed 20000 requests
- Completed 30000 requests
- Completed 40000 requests
- Completed 50000 requests
- Completed 60000 requests
- Completed 70000 requests
- Completed 80000 requests
- Completed 90000 requests
- Completed 100000 requests
- Finished 100000 requests
- Server Software:
- Server Hostname: localhost
- Server Port: 80
- Document Path: /test
- Document Length: 347 bytes
- Concurrency Level: 100
- Time taken for tests: 50.270 seconds
- Complete requests: 100000
- Failed requests: 0
- Write errors: 0
- Total transferred: 48712175 bytes
- HTML transferred: 34708675 bytes
- Requests per second: 1989.24 [#/sec] (mean)
- Time per request: 50.270 [ms] (mean)
- Time per request: 0.503 [ms] (mean, across all concurrent requests)
- Transfer rate: 946.29 [Kbytes/sec] received
- Connection Times (ms)
- min mean[+/-sd] median max
- Connect: 0 23 15.3 21 714
- Processing: 2 27 19.8 24 724
- Waiting: 1 22 15.4 20 714
- Total: 9 50 25.3 44 747
- Percentage of the requests served within a certain time (ms)
- 50% 44
- 66% 49
- 75% 53
- 80% 55
- 90% 64
- 95% 73
- 98% 87
- 99% 101
- 100% 747 (longest request)
三、使用HTTP 后的benchmark
Java代码
- Benchmarking localhost (be patient)
- Completed 10000 requests
- Completed 20000 requests
- Completed 30000 requests
- Completed 40000 requests
- Completed 50000 requests
- Completed 60000 requests
- Completed 70000 requests
- Completed 80000 requests
- Completed 90000 requests
- Completed 100000 requests
- Finished 100000 requests
- Server Software: Apache-Coyote/1.1
- Server Hostname: localhost
- Server Port: 80
- Document Path: /test
- Document Length: 347 bytes
- Concurrency Level: 100
- Time taken for tests: 55.392 seconds
- Complete requests: 100000
- Failed requests: 0
- Write errors: 0
- Total transferred: 51415934 bytes
- HTML transferred: 34710757 bytes
- Requests per second: 1805.32 [#/sec] (mean)
- Time per request: 55.392 [ms] (mean)
- Time per request: 0.554 [ms] (mean, across all concurrent requests)
- Transfer rate: 906.47 [Kbytes/sec] received
- Connection Times (ms)
- min mean[+/-sd] median max
- Connect: 0 24 10.1 24 185
- Processing: 8 31 10.7 28 215
- Waiting: 1 26 10.0 24 198
- Total: 13 55 12.3 51 247
- Percentage of the requests served within a certain time (ms)
- 50% 51
- 66% 54
- 75% 58
- 80% 60
- 90% 66
- 95% 74
- 98% 86
- 99% 99
- 100% 247 (longest request)
四、结论
If integration with the native webserver is needed for any reason,
an AJP connector will provide faster performance than proxied HTTP.
前端apache，后端tomcat，通过ajp协议访问性能优于http协议，随着并发量的提升，效果会更加趋于明显。可以从吞吐率和总时间开销上观察。
（吞吐率：单位时间内计算机的处理请求来描述其并发处理能力）
可以参考下ajp协议的设计 http://httpd.apache.org/docs/2.2/mod/mod_proxy_ajp.html
原因总结如下：
1、ajp使用长连接保持webServer和servlet Container的通信，减少了建立tcp连接的开销。可以通过观察tomcat/manager 下serverStatus，ajp建立的连接都处于keepalive的状态。
2、ajp使用一定的协议格式，减少了传递的报文数据大小，节省了带宽。可以通过观察ajp和http 的benchmark报告重看到，Total transferred 一项有明显的区别。