gistfile1.rb

$val = :hi

$outer = false
$inner = false

t1 =  Thread.new do
        begin
          $outer = true

          t2 = Thread.new do
                  begin
                    $inner = true
                    sleep
                  ensure
                    $val = :moo
                  end
                end

          until $inner
            Thread.pass
          end

          Thread.current.kill

        ensure
          t2.kill
          t2.join
        end
      end

until $outer and $inner
  Thread.pass
end

#t1.kill
t1.join

p $val