crystal_cluster.cr

require "http/server"

class Cluster
  def initialize(@n : Int32, @port : Int32, @io : IO = STDOUT)
    @workers = Array(Process).new
    @pid = Process.pid
  end

  def call
    head
    @n.times do |i|
      @workers << Process.fork do
        log(i)
        server.listen
      end
    end
    sleep
  ensure
    kill_all
  end

  private def kill_all
    @workers.each(&.kill)
  end

  private def server
    HTTP::Server.new(@port) do |context|
      context.response.print "Hello World"
    end
  end

  private def head
    @io.puts "[#{@pid}] * Listening on tcp://0.0.0.0:#{@port}", "[#{@pid}] Use Ctrl-C to stop"
  end

  private def log(i)
    @io.puts "[#{@pid}] - Worker #{i} (pid: #{Process.pid}) booted"
  end
end

n = ARGV[0]? || "4"
cluster = Cluster.new(n.to_i, 9292)
cluster.call