Hi, (Sent again, somehow my editor started to sometimes screw up mail headers, and ate the From:, sorry for the duplicate)
On 2022-04-15 12:36:52 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On April 15, 2022 11:23:40 AM EDT, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> The something is the logical replication launcher. In the failing runs, > >> it is advertising xmin = 724 (the post-initdb NextXID) and continues to > >> do so well past the point where tenk1 gets vacuumed. > > > That explains it. Before shmstat autovac needed to wait for the stats > > collector to write out stats. Now it's near instantaneous. So the issue > > probably existed before, just unlikely to ever be reached. > > Um, this is the logical replication launcher, not the autovac > launcher. Short term confusion... > Your observation that a sleep in get_database_list() reproduces it > confirms that I don't understand what you mean here? get_database_list() is autovac launcher code? So being able to reproduce the problem by putting in a sleep there doesn't seem like a confirm anything about the logical rep launcher? > , and I don't entirely see why the timing of the LR launcher > would have changed. Could still be related to the autovac launcher not requesting / pgstats not writing / launcher not reading the stats file(s). That obviously is going to have some scheduler impact. > > We can't just ignore database less xmins for non-shared rels, because > > walsender propagates hot_standby_feedback that way. But we can probably add > > a flag somewhere indicating whether a database less PGPROC has to be > > accounted in the horizon for non-shared rels. > > Yeah, I was also thinking about a flag in PGPROC being a more reliable > way to do this. Is there anything besides walsenders that should set > that flag? Not that I can think of. It's only because of hs_feedback that we need to. I guess it's possible that somebody build some extension that needs something similar, but then they'd need to set that flag... Greetings, Andres Freund
