> I recommend against using them. Maybe you can explain what you do and I can suggest a way
> to avoid using the
deferred transition.

I've only recently picked up the code and I'm not sure how it was envisioned when
initially designed, so here's my guess at how it's being used.

Deferred transition is registered by the FPN00
(main clock) process to make sure the logger has finished logging all events before continuing to stop readout
of other frontends. There is also a timeout, in case sometimes an event goes missing, to proceed with the run
stop without getting stuck waiting for the logger.

If there is a better way to implement this then I'm happy to
give it a go.

> P.S. I do not remember any use of deferred transition in the T2K/ND280 FGD, TPC and GSC
frontends,
> maybe it is in some other subsystem or was introduced after my time.

This is all from the global
DAQ code, so indeed none of the other subsystems' frontends use the feature directly. But if the clock module
frontend is started then run stops should be deferred.

Interestingly, I just checked and this feature is
disabled in the FGD ODB, but it is enabled in the TPC ODB.

Regards,
Yiwen.