If you start two instances, the second one will have a lot of port conflicts but won't terminate (and with nohup, there is nothing to ctrl-break) so the only way to kill it is to send a signal to the process.
Finally, kill -QUIT or -TERM signaled it to perform a shudown.
(not sure which, because I sent both)
-QUIT just causes it to print a Full thread dump to the logs.
-TERM causes what seems to be a regular shutdown (I just took a quick look, might be different from a regular shutdown)