Re: [PATCH] Disable bgworkers during servers start in pg_upgrade

Hi,

On 2021-08-27 09:34:24 +0800, Julien Rouhaud wrote:
> On Fri, Aug 27, 2021 at 7:31 AM Michael Paquier <michael@paquier.xyz> wrote:
> >
> > Indeed, there is some history here with autovacuum.  I have not been
> > careful enough to check that.  Still, putting a check on
> > IsBinaryUpgrade in bgworker_should_start_now() would mean that we
> > still keep track of the set of bgworkers registered in shared memory.
> 
> That shouldn't lead to any problem right?
> 
> > Wouldn't it be better to block things at the source, as of
> > RegisterBackgroundWorker()?  And that would keep track of the control
> > we have on bgworkers in a single place.  I also think that we'd better
> > document something about that either in bgworker.sgml or pg_upgrade's
> > page.
> 
> I'm fine with that approach too.

Isn't that just going to end up with extension code erroring out and/or
blocking waiting for a bgworker to start?

Greetings,

Andres Freund