non-volatile.rb

class Foo
  def initialize
    @var = 0
    # pad the variables apart to try to force them onto different cache lines
    32.times do |i|
      eval "@pad#{i} = nil"
    end
    @updated = false
  end

  def update
    @updated = true
    @var = 42
  end

  def check
    raise if @var == 42 && !@updated
    @updated
  end
end

100.times do
  100.times do
    obj = Foo.new
    t1 = Thread.new {
      sleep 0.01
      obj.update
    }
    100.times.map {
      Thread.new {
        Thread.pass while !obj.check
      }
    }.each(&:join)
    t1.join
  end
  puts 'another done'
end