Re: subscription/015_stream sometimes breaks

On Wed, Aug 23, 2023 at 1:31 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2023-Aug-23, Zhijie Hou (Fujitsu) wrote:
>
> > [1]--
> >               LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
> >
> >               workers = logicalrep_workers_find(MyLogicalRepWorker->subid, true);
> >               foreach(lc, workers)
> >               {
> >                       LogicalRepWorker *w = (LogicalRepWorker *) lfirst(lc);
> >
> > **                    if (isParallelApplyWorker(w))
> >                               logicalrep_worker_stop_internal(w, SIGTERM);
> >               }
>
> 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.

> 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.
>
> And the reason 0002 does not remove the zeroing of ->proc is that the
> tests gets stuck when I do that, and the reason for that looks to be
> some shoddy coding in WaitForReplicationWorkerAttach, so I propose we
> change that too, as in 0003.
>

Personally, I think we should consider this change (0002 and 0002) separately.

-- 
With Regards,
Amit Kapila.