Re: hash_xlog_split_allocate_page: failed to acquire cleanup lock

On Wed, Oct 12, 2022 at 4:16 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Thu, 6 Oct 2022 at 12:44, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Sat, Oct 1, 2022 at 12:35 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > >
> > > This issue does occasionally happen in CI, as e.g. noted in this thread:
> > > https://www.postgresql.org/message-id/20220930185345.GD6256%40telsasoft.com
> > >
> > > On 2022-08-18 15:17:47 +0530, Amit Kapila wrote:
> > > > I agree with you that getting rid of the clean-up lock on the new
> > > > bucket is a more invasive patch and should be done separately if
> > > > required. Yesterday, I have done a brief analysis and I think that is
> > > > possible but it doesn't seem to be a good idea to backpatch it.
> > >
> > > My problem with this approach is that the whole cleanup lock is hugely
> > > misleading as-is. As I noted in
> > > https://www.postgresql.org/message-id/20220817193032.z35vdjhpzkgldrd3%40awork3.anarazel.de
> > > we take the cleanup lock *after* re-initializing the page. Thereby
> > > completely breaking the properties that a cleanup lock normally tries to
> > > guarantee.
> > >
> > > Even if that were to achieve something useful (doubtful in this case),
> > > it'd need a huge comment explaining what's going on.
> > >
> >
> > Attached are two patches. The first patch is what Robert has proposed
> > with some changes in comments to emphasize the fact that cleanup lock
> > on the new bucket is just to be consistent with the old bucket page
> > locking as we are initializing it just before checking for cleanup
> > lock. In the second patch, I removed the acquisition of cleanup lock
> > on the new bucket page and changed the comments/README accordingly.
> >
> > I think we can backpatch the first patch and the second patch can be
> > just a HEAD-only patch. Does that sound reasonable to you?
>
> Thanks for the patches.
> I have verified that the issue is fixed using a manual test upto
> REL_10_STABLE version and found it to be working fine.
>

Thanks for the verification. I am planning to push the first patch
(and backpatch it) next week (by next Tuesday) unless we have more
comments or Robert intends to push it.

--
With Regards,
Amit Kapila.