I’m writing a new web application using mod_perl 2.0. It’s heavy on network I/O so I’m doing some benchmarking and testing with simulated I/O to see just how many requests/second I can expect a single server to handle. While reading through Practical mod_perl I discovered one of the greatest tools ever: ab.

stone@moradin:~ $ ab -n 5000 -c 10 http://localhost/echo
This is ApacheBench, Version 2.0.41-dev < $Revision: 1.141 $> apache-2.0
Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright (c) 1998-2002 The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient)
Completed 500 requests
Completed 1000 requests
Completed 1500 requests
Completed 2000 requests
Completed 2500 requests
Completed 3000 requests
Completed 3500 requests
Completed 4000 requests
Completed 4500 requests
Finished 5000 requests

Server Software: Apache/2.0.54
Server Hostname: localhost
Server Port: 80

Document Path: /echo
Document Length: 33 bytes

Concurrency Level: 10
Time taken for tests: 2.326156 seconds
Complete requests: 5000
Failed requests: 0
Write errors: 0
Total transferred: 1145916 bytes
HTML transferred: 165132 bytes
Requests per second: 2149.47 [#/sec] (mean)
Time per request: 4.652 [ms] (mean)
Time per request: 0.465 [ms] (mean, across all concurrent requests)
Transfer rate: 481.05 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 0.7 1 8
Processing: 2 2 1.2 3 10
Waiting: 0 1 0.9 2 8
Total: 3 3 1.2 4 11
WARNING: The median and mean for the waiting time are not within a normal deviation
These results are probably not that reliable.

Percentage of the requests served within a certain time (ms)
50% 4
66% 4
75% 4
80% 4
90% 4
95% 5
98% 7
99% 7
100% 11 (longest request)

This is awesome. Not only does it rock, but it’s included by default with Apache.