gistfile1.rb

# config.ru
module Server
  def self.call(env)
    body = File.read("index.html")
    [200, { "Content-Type" => "text/html", "Content-Length" => body.bytesize.to_s }, [body]]
  end
end

run Server

# rainbows.rb
worker_processes 1

Rainbows! do
  worker_connections 1000
  use :EventMachine
  keepalive_requests 1000
  keepalive_timeout 10
end

# in your shell
# install rainbows
gem install rainbows
# fire it
rainbows -c rainbows.rb -E production
./wrk -c32 -r10000 http://0.0.0.0:8080/

# I've got this
#=> Requests/sec:  13692.03

# Then you can add some CPU :) by changing `worker_processes` in rainbows.rb
# On my two core CPU with 2 workers I've got
#=> Requests/sec:  23642.73