main.rb

require "socket"

server = TCPServer.open("127.0.0.1", 50000);

puts "Server is running at 50000."

loop {
  begin
    parent = server.accept();

    # 省略

    threads.each { |thread|
      thread.join();
    }
  rescue
    parent.close();
    child.close();
    puts("Game End");
  end
}