A threaded counter implementation in Ruby

thread_counter.rb

#!/usr/bin/env ruby
require 'singleton'
require 'thread'

# Test to see if I remember how to use threads in Ruby properly
class ThreadCounter
  include Singleton

  NUM_THREADS = 4

  def initialize
    @count = 0
    @mutex = Mutex.new
    @threads = []
  end

  def run
    (1..NUM_THREADS).each do |i|
      @threads << Thread.new { count_forever(i) }
    end
    @threads.each { |t| t.join }
  # For ctrl-c support
  rescue SystemExit, Interrupt
    puts "Caught CTRL-C WE OUT"
    Thread.list.each { |t| Thread.kill(t) }
    return
  end

  def count_forever(thread_num)
    while true do
      sleep(rand*10)
      @mutex.synchronize { @count += 1 }
      puts "Thread #{thread_num}: #{@count}"
    end
  end

end

ThreadCounter.instance.run