threadthing.rb

class ThreadThing
  def initialize
    @threads = []
    @mutex = Mutex.new
    @shutdown = false
    trap('INT') { shutdown }
    trap('TERM') { shutdown }
  end

  def thread
    id = nil
    @mutex.synchronize { id = @threads.length } # just being lazy...
    @threads << Thread.new do
      loop do
        break if shutdown?
        print "#{id}"
        sleep 1
      end
    end
  end

  def shutdown?
    @shutdown
  end

  def shutdown
    @shutdown = true
  end

  def wait
    @threads.first.join
  end
end

puts $$
tt = ThreadThing.new
10.times { tt.thread }
tt.wait