preforking-echo-server.rb

require 'socket'
require 'kgio'

socket = Kgio::TCPServer.new '127.0.0.1', 4481

concurrency = 3
child_pids = []
sig_queue = []

concurrency.times do 
  child_pids << fork do
    trap(:INT) { exit }

    # heartbeat timestamp

    loop do
      connection = socket.kgio_tryaccept
      if connection
        connection.write connection.read
        connection.close
      end
    end
  end
end

trap(:CHLD) do
  sig_queue << :CHLD
end

trap(:INT) do
  sig_queue << :INT
end

loop do
  case sig_queue.shift
  when :INT
    child_pids.each do |cpid|
      Process.kill(:INT, cpid)
      sleep 0.5
    end

    exit
  when :CHLD
    puts 'child terminated unexpectedly'
  end
end

#Process.waitall