Horton

Re: TopoSort() fix

Rui Hai Jiang <ruihaij@gmail.com>

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From: Rui Hai Jiang <ruihaij@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-07-04T03:15:50Z
Lists: pgsql-hackers 
I'll try to figure out some  scenarios to do the test. A parallel process
group is needed for the test.

Actually I was trying to do some testing against the locking mechanism. I
happened to see this issue.

On Wed, Jul 3, 2019 at 9:38 PM Robert Haas <robertmhaas@gmail.com> wrote:

> On Tue, Jul 2, 2019 at 11:23 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Rui Hai Jiang <ruihaij@gmail.com> writes:
> > > I think I found an issue in the TopoSort() function.
> >
> > This indeed seems like a live bug introduced by a1c1af2a.
> > Robert?
>
> This is pretty thoroughly swapped out of my head, but it looks like
> that analysis might be correct.
>
> Is it practical to come up with a test case that demonstrates the problem?
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>

Commits

  1. Add an isolation test to exercise parallel-worker deadlock resolution.

  2. Mark advisory-lock functions as parallel restricted, not parallel unsafe.

  3. Fix busted logic for parallel lock grouping in TopoSort().