Re: race condition when writing pg_control

On Mon, Jun 08, 2020 at 03:25:31AM +0000, Bossart, Nathan wrote:
> On 6/7/20, 7:50 PM, "Thomas Munro" <thomas(dot)munro(at)gmail(dot)com> wrote:
>> I pushed 0001 and 0002, squashed into one commit. I'm not sure about
>> 0003. If we're going to do that, wouldn't it be better to just
>> acquire the lock in that one extra place in StartupXLOG(), rather than
>> introducing the extra parameter?
>
> Thanks! The approach for 0003 was discussed a bit upthread [0]. I do
> not have a strong opinion, but I lean towards just acquiring the lock.

Fujii-san has provided an answer upthread, that can maybe translated
as a +0.3~0.4:
https://www.postgresql.org/message-id/fc796148-7d63-47bb-e91d-e09b62a502e9@oss.nttdata.com

FWIW, I'd rather not take the lock as that's not necessary and just
add the parameter if I were to do it. Now I would be fine as well to
just take the lock if you decide that's more simple, as long as we add
this new assertion as a safety net for future changes.
--
Michael