Horton

Re: Connections hang indefinitely while taking a gin index's LWLock buffer_content lock

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Peter Geoghegan <pg@bowt.ie>, chenhj <chjischj@163.com>, Teodor Sigaev <teodor@sigaev.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-12-06T19:56:23Z
Lists: pgsql-hackers 
On Tue, Dec 4, 2018 at 8:01 PM Andres Freund <andres@anarazel.de> wrote:
> On 2018-11-10 17:42:16 -0800, Peter Geoghegan wrote:
> > On Wed, Nov 7, 2018 at 5:46 PM Peter Geoghegan <pg@bowt.ie> wrote:
> > > Teodor: Do you think that the issue is fixable? It looks like there
> > > are serious issues with the design of 218f51584d5 to me. I don't think
> > > the general "there can't be any inserters at this subtree" thing works
> > > given that we have to couple buffer locks when moving right for other
> > > reasons. We call ginStepRight() within ginFinishSplit(), for reasons
> > > that date back to bug fix commit ac4ab97e from 2013 -- that detail is
> > > probably important, because it seems to be what breaks the subtree
> > > design (we don't delete in two phases or anything in GIN).
> >
> > Ping?
> >
> > This is a thorny problem, and I'd like to get your input soon. I
> > suspect that reverting 218f51584d5 may be the ultimate outcome, even
> > though it's a v10 feature.
>
> Teodor, any chance for a response here?  It's not OK to commit something
> and then just not respond to bug-reports, especially when they're well
> diagnose and clearly point towards issues in a commit of yours.

Unfortunately, Teodor is unreachable at least till next week.

> Alexander, CCing you, perhaps you could point the thread out to Teodor?

I'll take a look at this issue.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Fix WAL format incompatibility introduced by backpatching of 52ac6cd2d0

  2. Fix wrong backpatching of ginRedoDeletePage() deadlock fix

  3. Fix deadlock in GIN vacuum introduced by 218f51584d5

  4. Prevent GIN deleted pages from being reclaimed too early

  5. Prevent deadlock in ginRedoDeletePage()

  6. Reduce page locking in GIN vacuum

  7. Fix race condition in GIN posting tree page deletion.