When upgrading to monit 5.16 on SLES 11 SP4 (x86_64), I noticed that monit-5.15 won't be stopped. Even when manually killing the only monit PID, it doesn't stop. Monit is not hung, however, because "monit summary" displays the configured services. As it turned out, monit eventually stopped, but with a significant delay (>5 seconds). That delay was too large for killproc to be successful.
Issue #328 on hold