Re: error context for vacuum to include block number

On Sat, Mar 28, 2020 at 06:59:10AM +0530, Amit Kapila wrote:
> On Sat, Mar 28, 2020 at 6:46 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> >
> > On Sat, Mar 28, 2020 at 06:28:38AM +0530, Amit Kapila wrote:
> > > > 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.
> > >
> > > pg_sleep internally uses CHECK_FOR_INTERRUPTS() due to which it would
> > > have accepted the signal sent via pg_cancel_backend(). Can you try
> > > your scenario by temporarily removing CHECK_FOR_INTERRUPTS from
> > > pg_sleep() or maybe better by using OS Sleep call?
> >
> > Ah, that explains it. Right, I'm not able to induce a crash with usleep().
> >
> > Do you want me to resend a patch without that change ? I feel like continuing
> > to trade patches is more likely to introduce new errors or lose someone else's
> > changes than to make much progress. The patch has been through enough
> > iterations and it's very easy to miss an issue if I try to eyeball it.
>
> I can do it but we have to agree on the other two points (a) I still
> feel that switching to the truncate phase should be done at the place
> from where we are calling lazy_truncate_heap and (b)
> lazy_cleanup_index should switch back the error phase after calling
> index_vacuum_cleanup. I have explained my reasoning for these points
> a few emails back.

I have no objection to either. It was intuitive to me to do it how I
originally wrote it but I'm not wedded to it.

--
Justin