Re: Patch to address creation of PgStat* contexts with null parent context

At Mon, 5 Sep 2022 08:52:44 +0200, "Drouvot, Bertrand" <bdrouvot(at)amazon(dot)com> wrote in
> Could using TopMemoryContext like in the attach be an option? (aka
> changing CacheMemoryContext by TopMemoryContext in the 3 places of
> interest): that would ensure the 3 pgStat* contexts to have a non NULL
> parent context.

Of course it works. The difference from what I last proposed is
whether we postpone creating the memory contexts until the first call
to pgstat_get_entry_ref(). The rationale of creating them at
pgstat_attach_shmem is that anyway once pgstat_attach_shmem is called,
the process fainally creates the contexts at the end of the process,
and (I think) it's simpler that we don't do if() check at every
pgstat_get_entry_ref() call.

I forgot about pgStatPendingContext, but it is sensible that we treat
it the same way to the other two.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center