test_server.rb

#!/usr/local/bin/macruby

server = Dispatch::Queue.new('my-server')
in_progress = Dispatch::Group.new

server.async(in_progress) do
  puts "Server running"

  server.suspend!

  puts "Queueing up remaining server process for later"
  server.async(in_progress) do
    puts "Server running again"
  end

  puts "Press return to continue the server"
  gets
  server.resume!
end

in_progress.wait