If you could post one of those

puppetserver_err_*.log

files to a Gist or Pastebin, there might be some clue as to what is eating RAM. It's not always the case that the thread that failed to allocate memory is the problem, but if the process is filling up within a minute then something may be in a tight look and the stacktrace will point a finger at it. I don't think there will be anything sensitive in there, just Java stack traces. But, give it look-over before posting.