Re: reorganize "Shared Memory and LWLocks" section of docs

Thanks for reviewing.

On Fri, Jan 12, 2024 at 05:12:28PM +0300, Aleksander Alekseev wrote:
> """
> Any registered shmem_startup_hook will be executed shortly after each
> backend attaches to shared memory.
> """
>
> IMO the word "each" here can give the wrong impression as if there are
> certain guarantees about synchronization between backends. Maybe we
> should change this to simply "... will be executed shortly after
> [the?] backend attaches..."

I see what you mean, but I don't think the problem is the word "each." I
think the problem is the use of passive voice. What do you think about
something like

Each backend will execute the registered shmem_startup_hook shortly
after it attaches to shared memory.

> """
> should ensure that only one process allocates a new tranche_id
> (LWLockNewTrancheId) and initializes each new LWLock
> (LWLockInitialize).
> """
>
> Personally I think that reminding the corresponding function name here
> is redundant and complicates reading just a bit. But maybe it's just
> me.

Yeah, I waffled on this one. I don't mind removing it.

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