Found while testing a 2.7.3 RC:
If you start the NodeManager and not the RM, the NM has a handler for SIGTERM and SIGINT that blocked my Ctrl-C and kill attempts during startup. I had to kill -9 it.
Steve Loughran tells me that this is potentially addressed by YARN-679, though that's a large patch.
Can't kill nodemanager process when running in the foreground