Horton

Re: REL_11_STABLE: dsm.c - cannot unpin a segment that is not pinned

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-02-17T20:35:37Z
Lists: pgsql-hackers 
On Mon, Feb 18, 2019 at 09:26:53AM +1300, Thomas Munro wrote:
> On Mon, Feb 18, 2019 at 9:07 AM Justin Pryzby <pryzby@telsasoft.com> wrote:
> > Actually...
> >
> > On killing the postmaster having completed this stress test, one of the
> > backends was left running and didn't die on its own.  It did die gracefully
> > when I killed the backend or the client.
> >
> > I was able to repeat the result, on first try, but took numerous attempts to
> > repeat the 2nd and 3rd time to save pg_stat_activity.
> >
> > Is there some issue regarding dsm_postmaster_shutdown ?
> 
> Huh.  What exactly do you mean by "killing the postmaster"?  If you
> mean SIGKILL or something, one problem with 11 is that

I mean unqualified /bin/kill which is kill -TERM (-15 in linux).

I gather (pun acknowledged but not intended) you mean "one problem with PG v11"
and not "one problem with kill -11" (which is what I first thought, although I
was somehow confusing kill -9, and since I don't know why anyone would ever
want to manually send SIGSEGV).

I think you're suggesting that's a known issue with v11, so nothing to do.

Thanks,
Justin

Commits

  1. Fix inconsistent out-of-memory error reporting in dsa.c.

  2. Fix race in dsm_unpin_segment() when handles are reused.

  3. Fix race in dsm_attach() when handles are reused.

  4. Fix rare dsa_allocate() failures due to freepage.c corruption.

  5. Add WL_EXIT_ON_PM_DEATH pseudo-event.