Programming Elixir 1.3

Process Overhead

At the start of the chapter, I somewhat cavalierly said Elixir processes were very low overhead. Now it is time to back that up. Let’s write some code that creates n processes. The first will send a number to the second. It will increment that number and pass it to the third. This will continue until we get to the last process, which will pass the number back to the top level.

spawn/chain.exs

defmodule Chain do
  def counter(next_pid) do    
    receive do
      n ->
        send next_pid, n + 1
    end
  end

  def create_processes(n) do
    last = Enum.reduce 1..n, self,
             fn (_,send_to) -> 
               spawn(Chain, :counter, [send_to])
             end

    send last, 0     # start the count by sending a zero to the last ...