Barebones HTTP server cluster in Crystal lang

http_cluster.cr

require "http/server"

module HTTPCluster
  struct Worker
    def initialize(@pid : Int32, @master : Int32)
    end

    def call(port)
      yield(port)
    end

    def kill
      Process.kill(Signal::KILL, @pid)
    end
  end

  class Cluster
    def initialize(@n : Int32, @handler : HTTP::Handler)
      @master = Process.pid
      @workers = [] of Worker
    end

    def start
      @n.times do |i|
        fork do
          worker = Worker.new(Process.pid, @master)
          @workers << worker 
          worker.call(9292 + i) do |port|
            puts "Listening on http://127.0.0.1:#{port}"
            HTTP::Server.new(port, @handler).listen
          end
        end
      end 
      loop {}
    ensure
      stop
    end

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

n = ARGV[0]? || 7

class HelloWorld < HTTP::Handler
  def call(context)
    context.response.content_type = "text/plain"
    context.response.print "Hello World"
  end
end

cluster = HTTPCluster::Cluster.new(n.to_i, HelloWorld.new)
cluster.start

processes_cluster.cr

require "socket"

struct Cluster
  def initialize(@n : Int32, @host : String, @port : Int32, @message : String)
    @server = TCPServer.new(@host, @port)
    @pids = [] of Int32
  end

  def call
    @n.times do
      fork do
        pid = Process.pid
        @pids << pid
        puts "child #{pid} accepting on shared socket (#{@host}:#{@port})"
        loop {
          @server.accept do |socket|
            socket.puts response
            socket.close
          end
        }
        exit
      end
    end
    loop {}
  ensure
    cleanup
  end

  private def response
    String.build do |str|
      str << "HTTP/1.1 200 OK\r\n"
      str << "Content-Type: text/plain\r\n"
      str << "Content-Length: #{@message.bytesize}\r\n"
      str << "Connection: keep-alive\r\n"
      str << "\r\n"
      str << @message
    end
  end

  private def cleanup
    @pids.each do |pid|
      Process.kill(Signal::KILL, pid)
    end
  end
end

n = ARGV[0]? || 3
host = ARGV[1]? || "localhost"
port = ARGV[2]? || 9292
message = ARGV[3]? || "Hello World"
Cluster.new(n.to_i, host, port.to_i, message).call

that's great