10.2.x has communication issues in both single and multi machine sites that at times resulted in a persistant .glock file remaining when modifying services under load. I usually experienced this on my production site when overwriting services when I set my min pooling instance to 0.
When the lock occurs, you will have to stop the ArcServer.exe process on each machine and then delete the lock file if it doesn't auto-kill when you stop the site. Killing the lock has no adverse affects.
Server at 10.3 has optimized communication between server machines - I no longer experience this lock.