Re: subscription/015_stream sometimes breaks

On Thu, Aug 24, 2023 at 8:18 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Thu, Aug 24, 2023 at 1:20 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> >
> > On 2023-Aug-24, Amit Kapila wrote:
> >
> > > On Wed, Aug 23, 2023 at 1:31 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> >
> > > > Hmm, I think if worker->in_use is false, we shouldn't consult the rest
> > > > of the struct at all, so I propose to add the attached 0001 as a minimal
> > > > fix.
> > >
> > > I think that way we may need to add the check for in_use before
> > > accessing each of the LogicalRepWorker struct fields or form some rule
> > > about which fields (or places) are okay to access without checking
> > > in_use field.
> >
> > As far as I realize, we have that rule already. It's only a few
> > relatively new places that have broken it. I understand that the in_use
> > concept comes from the one of the same name in ReplicationSlot, except
> > that it is not at all documented in worker_internal.h.
> >
> > So I propose we do both: apply Zhijie's patch and my 0001 now; and
> > somebody gets to document the locking design for LogicalRepWorker.
> >
>
> Agreed.

Both of these patches (Hou-san's expedient resetting of the worker
type, Alvaro's 0001 putting the 'in_use' check within the isXXXWorker
type macros) appear to be blending the concept of "type" with whether
the worker is "alive" or not, which I am not sure is a good thing. IMO
the type is the type forever, so I felt type should get assigned only
once when the worker is "born". For example, a dead horse is still a
horse.

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Kind Regards,
Peter Smith.
Fujitsu Australia