Hi,
You may be interested in this thread…
One way I would consider is create a DB resource eg new table called lock with a single row. Hence on instance start have a task update lock set locked = true where lock = false. If this succeeds, continue, otherwise abort. You also need a completion task - update lock set locked = false.
I suspect the pattern you are after is a network semaphore. Another approach could be to look at something like zookeeper
regards
Rob