Re: shared-memory based stats collector - v70

At Tue, 9 Aug 2022 09:53:19 -0700, Andres Freund <andres(at)anarazel(dot)de> wrote in
> Hi,
>
> On 2022-08-09 17:24:35 +0900, Kyotaro Horiguchi wrote:
> > If I'm not missing something, it's strange that pgstat_lock_entry()
> > only takes LW_EXCLUSIVE.
>
> I think it makes some sense, given that there's a larger number of callers for
> that in various stats-emitting code. Perhaps we could just add a separate
> function with a _shared() suffix?

Sure. That was an alternative I had in my mind.

> > The atached changes the interface of
> > pgstat_lock_entry() but there's only one user since another read of
> > shared stats entry is not using reference. Thus the interface change
> > might be too much. If I just add bare LWLockAcquire/Release() to
> > pgstat_fetch_entry,the amount of the patch will be reduced.
>
> Could you try the pgstat_lock_entry_shared() approach?

Of course. Please find the attached.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center