Re: Recent "could not register background process" buildfarm failures

> On 18 Aug 2026, at 19:44, Álvaro Herrera <alvherre(at)kurilemu(dot)de> wrote:
>
> On 2026-Aug-18, Tom Lane wrote:
>
>> # +ERROR: could not register background process
>> # +HINT: You may need to increase "max_worker_processes".
>>
>> test_shm_mq itself hasn't changed meaningfully in ages,
>> so it seems like some recent change somewhere else has increased
>> the probability of not being able to get a worker process.
>> Maybe autovacuum is eating too many workers? Any thoughts?
>
> Hm, autovacuum does not use workers from the bgworker pool AFAIK.
> Repack concurrently does. However, I don't think we use repack
> concurrently anywhere in the standard tests; we only run it in the
> test_decoding and injection_point tests, which have separate instances.

Online checksums also use bgworkers but it too should not be running here, and
looking at it I didn't see evidence of it interfering. I'll have another look
in the morning with fresh eyes.

--
Daniel Gustafsson