Re: error context for vacuum to include block number

On Fri, Mar 27, 2020 at 11:50:30AM +0530, Amit Kapila wrote:
> > > The crash scenario I'm trying to avoid would be like statement_timeout or other
> > > asynchronous event occurring between two non-atomic operations.
> > >
> > +if (errinfo->phase==VACUUM_ERRCB_PHASE_VACUUM_INDEX && errinfo->indname==NULL)
> > +{
> > +kill(getpid(), SIGINT);
> > +pg_sleep(1); // that's needed since signals are delivered asynchronously
> > +}
> > I'm not sure if those are possible outside of "induced" errors. Maybe the
> > function is essentially atomic due to no CHECK_FOR_INTERRUPTS or similar?
>
> Yes, this is exactly the point. I think unless you have
> CHECK_FOR_INTERRUPTS in that function, the problems you are trying to
> think won't happen.

Hm, but I caused a crash *without* adding CHECK_FOR_INTERRUPTS, just
kill+sleep. The kill() could come from running pg_cancel_backend(). And the
sleep() just encourages a context switch, which can happen at any time. I'm
not convinced that the function couldn't be interrupted by a signal.

--
Justin