Re: Implement waiting for wal lsn replay: reloaded

Hi Thomas,

On Tue, Jan 6, 2026 at 1:43 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
>
> Could this be causing the recent flapping failures on CI/macOS in
> recovery/031_recovery_conflict? I didn't have time to dig personally
> but f30848cb looks relevant:
>
> Waiting for replication conn standby's replay_lsn to pass 0/03467F58 on primary
> error running SQL: 'psql:<stdin>:1: ERROR: canceling statement due to
> conflict with recovery
> DETAIL: User was or might have been using tablespace that must be dropped.'
> while running 'psql --no-psqlrc --no-align --tuples-only --quiet
> --dbname port=25195
> host=/var/folders/g9/7rkt8rt1241bwwhd3_s8ndp40000gn/T/LqcCJnsueI
> dbname='postgres' --file - --variable ON_ERROR_STOP=1' with sql 'WAIT
> FOR LSN '0/03467F58' WITH (MODE 'standby_replay', timeout '180s',
> no_throw);' at /Users/admin/pgsql/src/test/perl/PostgreSQL/Test/Cluster.pm
> line 2300.
>
> https://cirrus-ci.com/task/5771274900733952
>
> The master branch in time-descending order, macOS tasks only:
>
> task_id | substring | status
> ------------------+-----------+-----------
> 6460882231754752 | c970bdc0 | FAILED
> 5771274900733952 | 6ca8506e | FAILED
> 6217757068361728 | 63ed3bc7 | FAILED
> 5980650261446656 | ae283736 | FAILED
> 6585898394976256 | 5f13999a | COMPLETED
> 4527474786172928 | 7f9acc9b | COMPLETED
> 4826100842364928 | e8d4e94a | COMPLETED
> 4540563027918848 | b9ee5f2d | FAILED
> 6358528648019968 | c5af141c | FAILED
> 5998005284765696 | e212a0f8 | COMPLETED
> 6488580526178304 | b85d5dc0 | FAILED
> 5034091344560128 | 7dc95cc3 | ABORTED
> 5688692477526016 | bb048e31 | COMPLETED
> 5481187977723904 | d351063e | COMPLETED
> 5101831568752640 | f30848cb | COMPLETED <-- the change
> 6395317408497664 | 3f33b63d | COMPLETED
> 6741325208354816 | 877ae5db | COMPLETED
> 4594007789010944 | de746e0d | COMPLETED
> 6497208998035456 | 461b8cc9 | COMPLETED

Thanks for raising this issue. I think it is related to f30848cb after
some analysis. I'll prepare a follow-up patch to fix it.

--
Best,
Xuneng