Re: Let's make PostgreSQL multi-threaded

On Mon, Jun 5, 2023 at 04:50:11PM -0700, Peter Geoghegan wrote:
> On Mon, Jun 5, 2023 at 4:26 PM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > I remember we used to have macros we called before we modified critical
> > parts of shared memory, and if a process exited while in those blocks,
> > the server would restart. Unfortunately, I can't find that in the code
> > now.
>
> Isn't that what we call a critical section? They effectively "promote"
> any ERROR (e.g., from an OOM) into a PANIC.
>
> I thought that we only used critical sections for things that are
> WAL-logged, but I double checked just now. Turns out that I was wrong:
> PGSTAT_BEGIN_WRITE_ACTIVITY() contains its own START_CRIT_SECTION(),
> despite not being involved in WAL logging. And so critical sections
> could indeed be described as something that we use whenever shared
> memory cannot be left in an inconsistent state (which often coincides
> with WAL logging, but need not).

Yes, sorry, critical sections is what I was remembering. My question is
whether all unexpected backend exits should be treated as critical
sections?

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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