README.md

Minimal Test for Sinatra: single global vs each request

Setup to show the difference between the different ways of using set in Sinatra::App.

Run it

bundle exec puma -C ./puma.rb

And then make some calls from another shell:

# test single
ab -n 10 -c 1 http://127.0.0.1:3333/one

# test each
ab -n 10 -c 1 http://127.0.0.1:3333/each

app.rb

# frozen_string_literal: true
require 'logger'
require 'sinatra/base'
require 'sinatra/json'

class SomeSingleton
  MSG = 'I got called.'

  def initialize(logger)
    @logger = logger
    logger.info("==> Instance created! <==")
  end

  def call
    @logger.info("--> #{MSG}")
    MSG
  end
end

class App < Sinatra::Base
  set :log_device, STDOUT
  set :logger, -> { Logger.new(settings.log_device) }
  set :show_exceptions, false
  set :raise_errors, false
  set :dump_errors, false

  set :globally_one, SomeSingleton.new(logger)
  set :each_request, -> { SomeSingleton.new(logger) }

  before { content_type('application/json') }
  get('/one') { [200, json(Hash.new(msg: settings.globally_one.call))] }
  get('/each') { [200, json(Hash.new(msg: settings.each_request.call))] }
end

config.ru

# frozen_string_literal: true
require './app'
run App

Gemfile

# frozen_string_literal: true
source 'https://rubygems.org'

gem 'puma'
gem 'sinatra'
gem 'sinatra-contrib'

puma.rb

# frozen_string_literal: true
environment ENV['RACK_ENV'] || 'development'
workers 0 # no workers, just threads!
threads 2, 2
bind 'tcp://0.0.0.0:3333'
preload_app!