I expected :before, but foo volatility issue comes first

__typescript__

# on Ubuntu with 4 cores
% jruby -v
jruby 1.7.0.dev (ruby-1.9.3-p28) (2012-02-14 78244f2) (Java HotSpot(TM) 64-Bit Server VM 1.7.0_04-ea) [linux-amd64-java]
% while true; do jruby method_invalidate_2.rb; done
:after
:after
:after
:after
:after
:after
:after
:after
:after
:after
:after
:after
:after
:after
# => Never return with CPU 100%

method_invalidate_2.rb

def foo
  true
end

def bar
  :before
end

t = Thread.new {
  true while foo
  bar
}

sleep 1

def bar
  :after
end

def foo
  false
end
p t.join.value