Trample is a flexible load simulation tool.

Most load sim tools make requests to a static list of urls. They spawn n threads and make requests to the urls on the list in succession, in each thread. Unfortunately, though, if your applicaition makes use of any kind of caching (including your database’s internal caching facilities), this kind of load simulation is unrealistic.

The data required to serve a single set of urls is likely to fit nicely in the database server’s cache (even on a small server). So, having a single user hammer a finite set of pages will make your application look much faster than it really is.

Trample allows you to provide parameter values inside of a block (a lambda function, for non-rubyists). The block is executed each time the parameters are needed. So, if you use randomization in the block, you should (theoretically) get different values every time.

That way, you can have trample log in as several different users and request different data in each session.

Trample uses a ruby DSL for configuration.

Trample.configure do
  concurrency 5
  iterations  10
  login do
    post "http://yoursite.com/login" do
      {:username => User.random.username, :password => "swordfish"}
    end
  end
  get  "http://yoursite.com/somewhere"
  post "http://yoursite.com/something" do
    {:a_parameter => "a value"}
  end
  get  "http://yoursite.com/someresources/:id" do
    {:id => SomeResource.random.id}
  end
end

The above configuration will start 5 (concurrency) sessions by logging in as a random user at the url in the login block. Then, it’ll hit the two urls underneath it 10 (iterations) times during each session.

To run trample, save your configuration somewhere and run:

trample start /path/to/your/trample/config.rb

Copyright © 2009 James Golick. See LICENSE for details.