fetcher_image.rb

gistfile1.txt

require 'celluloid/current'
require 'rest-client'
require 'benchmark'

class ModelX
  attr_accessor :url
  def initialize(url)
    @url = url
  end
end

models = []
50.times.each { |i| models.push ModelX.new("http://httpbin.org/redirect-to?url=https://randomuser.me/api/portraits/med/women/#{i}.jpg") }

# create fetcher
class ImageFetcher
  include Celluloid

  def do(url)
    r = RestClient.get(url) # do same complex request here, and
    return {got: r.net_http_res.uri.to_s, requested: url}
  end


end

# create fetcher pool with size 20
pool = ImageFetcher.pool(size: 20)

def fetch(pool, urls)
  urls.map { |url| pool.future.do(url)  }.map(&:value)
end

Benchmark.bmbm(2) do |bm|
  bm.report('normal approach') do
    models.each do |model|
      ImageFetcher.new.do(model.url)
    end
  end

  bm.report('using futures') do
    fetch(pool, models.map(&:url)) # will returns a array with hash, the hash has the keys got and requested
  end
end

gistfile2.txt

ruby image_fetcher.rb                                            [ ruby-2.2.2p95 ]
Rehearsal ---------------------------------------------------
normal approach   0.400000   0.080000   0.480000 ( 45.859779)
using futures     0.360000   0.050000   0.410000 (  2.979211)
------------------------------------------ total: 0.890000sec

                      user     system      total        real
normal approach   0.360000   0.070000   0.430000 ( 48.330249)
using futures     0.360000   0.040000   0.400000 (  3.153157)