Thread::timeout.rb

class Thread
  class TimeoutError < StandardError; end
  def self.timeout(n)
    temp_queue = Queue.new
    work_thread = Thread.new { temp_queue << {return: yield} } # wrapping in a hash guarantees uniqueness of output
    timeout_thread = Thread.new { sleep n; temp_queue << :timeout }

    if (ret_val = temp_queue.pop) == :timeout  # this pop is blocking, so it either waits on the yield or the timeout
      work_thread.kill
      raise TimeoutError
    else
      timeout_thread.kill
      return ret_val[:return]
    end
  end
end

# This will either return "some val" or raise a Thread::Timeout
# Is raising an error a good idea?  I don't know.  The other
#  options were to return nil or return a special Timeout object
#  but I didn't like either of those, so I went with an error.
#  It's not much trouble to wrap this in a begin, and it
#  can be "dangerous", so I figured throwing an error was best.
Thread.timeout(1) do
  sleep rand*2 # simulate work that takes 0 to 2 seconds
  "some val"
end

# It actually feels pretty intuitive.
begin
  Thread.timeout(2) do
    (1..10000000000).reduce(:+)
  end
rescue Thread::TimeoutError
  puts "operation took longer than 2 seconds"
end