Ruby/Threads/sleep

interval = 1.0
10.times do |x|
  t1 = Time.new
  sleep(interval)
  actual = Time.new - t1
  difference = (actual-interval).abs
  percent_difference = difference / interval * 100
  printf("%.9f %.6f %.6f (%.2f%%)\n",interval, actual, difference, percent_difference)
  interval /= 10
end

Time.new                     # => Sat Mar 18 21:17:58 EST 2006
sleep(10)
Time.new                     # => Sat Mar 18 21:18:08 EST 2006
sleep(1)
Time.new                     # => Sat Mar 18 21:18:09 EST 2006

100.downto(1) { |c| print c, " "; sleep 1 }

puts Time.new.usec                        # => 377185
sleep(0.1)
puts Time.new.usec                        # => 479230

3.downto(1) { |i| puts "#{i}..."; sleep(1) }; puts "Go!"