gifs.rb

require 'typhoeus'

class Array; def in_groups(num_groups)
  return [] if num_groups == 0
  slice_size = (self.size/Float(num_groups)).ceil
  self.each_slice(slice_size).to_a
end; end

gifs = []
threads = []

gifs += File.open('gifs.txt').read.each_line.to_a

gifs.in_groups(16).each do |group|
  threads << Thread.new do
    group.each do |url|
      request = Typhoeus.get url
      puts url if request.code == 200
    end
  end
end

threads.each { |thr| thr.join }