Re: Set appropriate processing mode for auxiliary processes.

On Thu, May 9, 2024 at 11:19 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> > At first I was sure this was introduced by my refactorings in v17, but
> > in fact it's been like this forever. I agree that InitProcessing makes
> > much more sense. The ProcessingMode variable is initialized to
> > InitProcessing, so I think we can simply remove that line from
> > AuxiliaryProcessMainCommon(). There are existing
> > "SetProcessingMode(InitProcessing)" calls in other Main functions too
> > (AutoVacLauncherMain, BackgroundWorkerMain, etc.), and I think those can
> > also be removed.
>
> This only works if the postmaster can be trusted never to change the
> variable; else children could inherit some other value via fork().
> In that connection, it seems a bit scary that postmaster.c contains a
> couple of calls "SetProcessingMode(NormalProcessing)". It looks like
> they are in functions that should only be executed by child processes,
> but should we try to move them somewhere else?

After checking calls to "SetProcessingMode(NormalProcessing)" in the
postmaster.c, they are used in background worker specific functions
(BackgroundWorkerInitializeConnectionByOid and
BackgroundWorkerInitializeConnection). So I think it's a good idea to
move these functions to bgworker.c. Then, we can get rid of calling
"SetProcessingMode(NormalProcessing)" in postmaster.c.

I also noticed that there's an unnecessary call to
"BackgroundWorkerInitializeConnection" in worker_spi.c (The worker_spi
launcher has set the dboid correctly).

Best Regards,
Xing.