From: Fredrik <fredjoha@...>
Date: 2008-04-18T14:30:03+09:00
Subject: Re: Parallel for loop

>
> It's different with blocks:
>

Ah, I got it! So it should look like this then:

  def forkmap(n = nil)
    nproc = 0
    result = map do |*a|
      r, w = IO.pipe
      fork do
        r.close
        w.write( Marshal.dump( yield(*a) ) )
      end
      if n and (nproc+=1) >= n
        Process.wait ; nproc -= 1
      end
      [ w.close, r ].last
    end
    Process.waitall
    result.map{|r| Marshal.load [ r.read, r.close ].first}
  end


irb> Benchmark.realtime {[1,2,3].forkmap{|i| sleep 1 } }
=> 1.01688504219055
irb> Benchmark.realtime {[1,2,3].forkmap(1){|i| sleep 1 } }
=> 3.01162004470825

Thanks! That takes me to another level of Ruby knowledge :)

/Fredrik