Re: Fix 035_standby_logical_decoding.pl race conditions

On Wed, Apr 2, 2025 at 2:06 PM Bertrand Drouvot
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
>
> As far PG17-v4-0001:
>
>
> === 4
>
> It looks like that check_slots_conflict_reason() is not called with checks_active_slot
> as argument.
>
> === 5
>
> I think that we could remove the need for the drop_active_slot parameter in
> drop_logical_slots() and just check if an active slot exists (and if so drop
> it). That said I'm not sure it's worth to go that far for backpatching.
>

The other idea to simplify the changes for backbranches:
sub reactive_slots_change_hfs_and_wait_for_xmins
{
...
+  my ($slot_prefix, $hsf, $invalidated, $needs_active_slot) = @_;

  # create the logical slots
-  create_logical_slots($node_standby, $slot_prefix);
+  create_logical_slots($node_standby, $slot_prefix, $needs_active_slot);

...
+  if ($needs_active_slot)
+  {
+    $handle =
+     make_slot_active($node_standby, $slot_prefix, 1, \$stdout, \$stderr);
+  }

What if this function doesn't take input parameter needs_active_slot
and rather removes the call to make_slot_active? We will call
make_slot_active only at the required places. This should make the
changes much less because after that, we don't need to make changes
related to drop and create. Sure, in some cases, we will test two
inactive slots instead of one, but I guess that would be the price to
keep the tests simple and more like HEAD.

--
With Regards,
Amit Kapila.