Selectable process IO on JRuby...normally impossible on JVM

gistfile1.txt

system ~/projects/jruby $ cat process_select.rb 
io = open("|cat", "r+")
Thread.new {
  loop {
    sleep 1
    io.write("hello")
  }
}

Thread.new {
  loop {
    1 until IO.select([io])
    ret = io.read_nonblock(5, :exception => false)
    puts ret unless ret == :wait_readable
  }
}

sleep

system ~/projects/jruby $ jruby -v process_select.rb 
jruby 9000.dev-SNAPSHOT (2.1.2) 2014-05-22 1a2daf7 on Java HotSpot(TM) 64-Bit Server VM 1.7.0_45-b18 [darwin-x86_64]
hello
hello
hello
hello
hello
hello
hello
hello
hello
hello
hello
^C
system ~/projects/jruby $ rvm jruby do ruby -v process_select.rb 
jruby 1.7.12 (1.9.3p392) 2014-04-15 643e292 on Java HotSpot(TM) 64-Bit Server VM 1.7.0_45-b18 [darwin-x86_64]
HANGS!^C