Async request handling with sinatra and EM, freeze if request not exist URL

basic.ru

#!/usr/bin/env rackup -Ilib:../lib -s thin

# async message handling
# using gem https://github.com/raggi/async_sinatra

require 'sinatra/async'
require "em-http-request"
require 'open-uri'

require "em-synchrony"
require "em-synchrony/em-http"
require "em-synchrony/fiber_iterator"


module Handler
  extend self
  @queue = []

  def <<(value)
    @queue << value
  end

  def run
    return if @running
    @running = true

    EventMachine::PeriodicTimer.new(1) do
      concurrency = 5
      urls = @queue.shift(concurrency)
      if urls.any?
        puts "remain #{@queue.size}"
        EM.synchrony do
          EM::Synchrony::FiberIterator.new(urls, concurrency).each do |url|
            resp = EventMachine::HttpRequest.new(url).get
            if resp.response_header.status == 200
              puts "Message delivered"
            else
              puts "Error when get #{url} status #{resp.response_header.status}"
              @queue.push(url) #потом запросим повторно
            end
            puts "request complete #{resp.response_header.status}"
          end

        end

      end
    end

    puts "Handler started"
  end

end

class AsyncTest < Sinatra::Base
  register Sinatra::Async

  enable :show_exceptions

  before do
    Handler.run
  end

  aget '/send' do
    msg=params[:http]
    body "Added to queue: #{msg}"
    Handler << msg
  end

end

run AsyncTest.new