Re: subscription/015_stream sometimes breaks

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.

> > In fact, I'd go further and propose that if we do take that stance, then
> > we don't need clear out the contents of this struct at all, so let's
> > not. That's 0002.
>
> Personally, I think we should consider this change (0002 and 0002) separately.

I agree. I'd maybe even retract them.

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/