EventMachine with JRuby, running reactor inside a thread doesn't work

em_jruby_issue.rb

require 'eventmachine'

Thread.new{ EM.run }
until EM.reactor_running?; sleep 0.1; end

EM.add_periodic_timer(1){ puts "tick" }

sleep 5

shell output

bbozo@uhurajr-ubuntu:~/dev$ ruby -v
ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-linux]

bbozo@uhurajr-ubuntu:~/dev$ ruby em_jruby_problem.rb
tick
tick
tick
tick

bbozo@uhurajr-ubuntu:~/dev$ rvm use jruby
Using /home/bbozo/.rvm/gems/jruby-1.7.4

bbozo@uhurajr-ubuntu:~/dev$ ruby em_jruby_problem.rb

bbozo@uhurajr-ubuntu:~/dev$