pmapper.rb

require 'celluloid'

class PMapper
  include Celluloid

  def run(mailbox, i, elem, block)
    mailbox << [i, block.call(elem)]
  end
end

module Enumerable
  def pmap(&block)
    futures = map { |elem| Celluloid::Future.new(elem, &block) }
    futures.map { |future| future.value }
  end


  def pmap(workers = 16, &block)
    pool = PMapper.pool(:size => workers)
    mb = Celluloid::Mailbox.new

    i = 0
    each do |elem|
      pool.async.run(mb, i, elem, block)
      i += 1
    end

    res = []
    i.times do
      mb.receive { |(idx, value)| res[idx] = value }
    end
    res
  end
end

t = Time.now
p (1..32).pmap { |x| sleep 2; x * 2 }
p Time.now - t