Out-of-Cycle release? (was Re: BUG #19490: Streaming standby on 16.14 stops applying WAL on MultiXactOffsetSLRU when primary is 16.8)

Hi,

moving this to -hackers.

On Wed, May 27, 2026 at 12:06:45PM +0300, Heikki Linnakangas wrote:
> On 27/05/2026 05:55, Nazneen Jafri wrote:
> > Tested Andrey's demo.diff on a fresh environment:
> >
> >   - Primary: REL_16_8, Standby: REL_16_14 (--enable-cassert)
> >
> >   - ~2300 MultiXacts crossing the offsets page boundary
> >
> >   - Without patch: startup deadlocks at RecordNewMultiXact(multi=2047)
> >
> >   - With patch: standby replays all WAL and catches up
>
> Thanks all. I have applied this to v14 - v16.

I would like to suggest that this bug-fix might warrant an out-of-cylce
release (even though it is has been a month since the fix got
committed). There has been at least one more report on pgsql-bugs[1],
we (at credativ) have had a customer issue about it and Jan Karremans
(in CC) mentioned this on Telegram today as well.

To reiterate, this bug is a regression in the latest back-branch
releases for versions 14-16. If either the standby gets updated to the
latest minor release first, or if somebody does PITR from a primary on an
earlier release to an instance with the latest minor release, the
standby/PITR deadlocks and just sits there.

I think those are pretty important/usual use-cases, so even if versions
17/18 are not affected (to-the-best-of-my-knowledge), maybe 14-16 should
get a re-release for this? Or has this already been discussed among the
release team?

Regards,

Michael