Requiring grape hugely slows down Goliath

Question

I've written a 'Hello World' app using Goliath, and I decided to mount Grape on top of it:

#!/usr/bin/env ruby

require 'rubygems'
require 'bundler/setup'
Bundler.setup :default
require 'goliath'
require 'grape'   # <-- Comment out this line will hugely increase performance, but why?

class Server < Goliath::API
  def response(env)
    [200, {}, 'Hello, world!']
  end
end

I benchmarked it:

ab -n 1000 -c 100 http://localhost:9000/

It shows that about 250 requests can be handled per second. But when I comment out the line require 'grape', this value suddenly increased to about 700. Can anybody answer why the simple require can bring such a huge difference?

P.S. I use MRI 2.2.2

Answer 1

Are you running Goliath in production mode? You have to set -e prod of it will do code re-loading on each request.