RE: Fix 035_standby_logical_decoding.pl race conditions

Dear Bertrand, Amit,

> > I do prefer v5-PG17-2 as it is "closer" to HEAD. That said, I think that we should
> > keep the slots active and only avoid doing the checks for them (they are
> invalidated
> > that's fine, they are not that's fine too).
> >
> 
> I don't mind doing that, but there is no benefit in making slots
> active unless we can validate them. And we will end up adding some
> more checks, as in function check_slots_conflict_reason without any
> advantage. I feel Kuroda-San's second patch is simple, and we have
> fewer chances to make mistakes and easy to maintain in the future as
> well.

I have concerns for Bertrand's patch that it could introduce another timing
issue. E.g., if the activated slots are not invalidated, dropping slots is keep
being activated so the dropping might be fail. I did not reproduce this but
something like this can happen if we activate slots.

Attached patch has a conclusion of these discussions, slots are created but
it seldomly be activated.

Naming of patches are bit different, but please ignore...

Best regards,
Hayato Kuroda
FUJITSU LIMITED