YARN container has hidden processes after death

Question

I played with distributed shell examples, and I noticed that when I kill a long application, the process is saved. For example, if I remove the distshell application using sleep 1000 as a command a few seconds after the container starts, the process will still show

 yarn 33138 0.0 0.0 2432752 508 ?? S 12:20PM 0:00.00 sleep 1000 

I thought YARN would be good at cleaning up child processes? Perhaps this only applies to JAVA processes?