Do you want to synchronize JACK clients so they do
something in the same
cycle / at the same sample time?
Yes, I think so.
You could inject an event to JACK that's being
distributed to the clients
(inside JACK). The clients would then receive the events in the same cycle
and can process (at given sample pos) in that cycle.
This sounds very good. However, I am not sure what you mean in terms of code. Can you
please provide some example code?