Re: Estimating HugePages Requirements?

On Mon, May 09, 2022 at 03:53:24PM +0900, Michael Paquier wrote:
> I have looked at the patch posted at [1], and I don't quite understand
> why you need the extra dance with log_min_messages. Why don't you
> just set the GUC at the end of the code path in PostmasterMain() where
> we print non-runtime-computed parameters?

The log_min_messages dance avoids extra output when inspecting
non-runtime-computed GUCs, like this:

~/pgdata$ postgres -D . -C log_min_messages -c log_min_messages=debug5
debug5
2022-05-10 09:06:04.728 PDT [3715607] DEBUG: shmem_exit(0): 0 before_shmem_exit callbacks to make
2022-05-10 09:06:04.728 PDT [3715607] DEBUG: shmem_exit(0): 0 on_shmem_exit callbacks to make
2022-05-10 09:06:04.728 PDT [3715607] DEBUG: proc_exit(0): 0 callbacks to make
2022-05-10 09:06:04.728 PDT [3715607] DEBUG: exit(0)

AFAICT you need to set log_min_messages to at least DEBUG3 to see extra
output for the non-runtime-computed GUCs, so it might not be worth the
added complexity.

> I am not really worrying
> about users deciding to set log_min_messages to PANIC in
> postgresql.conf when it comes to postgres -C, TBH, as they'd miss the
> FATAL messages if the command is attempted on a server already
> starting.

I don't have a strong opinion on this one.

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com