Re: allow changing autovacuum_max_workers without restarting

On 28.04.25 16:41, Nathan Bossart wrote:
> On Mon, Apr 28, 2025 at 09:14:54AM -0400, Tom Lane wrote:
>> Peter Eisentraut <peter(at)eisentraut(dot)org> writes:
>>> This initdb output seems, well, kinda fake, which it is by its own
>>> admission.
>>
>> Agreed.
>>
>>> Could we do this less fake maybe like this:
>>> selecting default "max_connections", "autovacuum_worker_slots" ... 100, 16
>>> with the actual wait at the "..."?
>>
>> Perhaps that would be all right ...
>>
>>> (It doesn't seem impossible that someone will want to add more default
>>> selecting for various worker or process slots, and this would allow adding
>>> these easily, versus adding more "fake" output lines.)
>>
>> ... but I can't see this approach scaling to three or four or five
>> outputs. The line would get unreasonably long.
>>
>> My own proposal given the way it works now is to just print
>> max_connections and not mention autovacuum_worker_slots at all.
>> Our choice for max_connections is worth reporting, but I don't
>> feel that everything derived from it needs to be reported.
>
> I'm fine with either of these ideas. If I had to choose one, I'd just
> remove the autovacuum_worker_slots report for the reasons Tom noted.

Yes, removing the report is also fine by me.

> However, weren't we considering reverting some of this stuff [0]? I see
> that sawshark is now choosing max_connections = 40 and
> autovacuum_worker_slots = 6, and since there are no other apparent related
> buildfarm failures, I'm assuming that nobody else is testing the 60
> semaphores case anymore.
>
> [0] https://postgr.es/m/618497.1742347456%40sss.pgh.pa.us

(I don't have any thoughts on this.)