Re: [HACKERS] Weaker shmem interlock w/o postmaster.pid

On Thu, Nov 29, 2018 at 10:51:40PM -0800, Noah Misch wrote:
> On Thu, Nov 29, 2018 at 01:10:57PM +0100, Dmitry Dolgov wrote:
> > As a side note, with this patch recovery tests are failing now on 016_shm.pl
> > 
> > #   Failed test 'detected live backend via shared memory'
> > #   at t/016_shm.pl line 87.
> > #                   '2018-11-28 13:08:08.504 UTC [21924] LOG:
> > listening on Unix socket "/tmp/yV2oDNcG8e/gnat/.s.PGSQL.512"
> > # 2018-11-28 13:08:08.512 UTC [21925] LOG:  database system was
> > interrupted; last known up at 2018-11-28 13:08:08 UTC
> > # 2018-11-28 13:08:08.512 UTC [21925] LOG:  database system was not
> > properly shut down; automatic recovery in progress
> > # 2018-11-28 13:08:08.512 UTC [21925] LOG:  invalid record length at
> > 0/165FEF8: wanted 24, got 0
> > # 2018-11-28 13:08:08.512 UTC [21925] LOG:  redo is not required
> > # 2018-11-28 13:08:08.516 UTC [21924] LOG:  database system is ready
> > to accept connections
> > # '
> > #     doesn't match '(?^:pre-existing shared memory block)'
> 
> Thanks for the report.  Since commit cfdf4dc made pg_sleep() react to
> postmaster death, the test will need a different way to stall a backend.  This
> doesn't affect non-test code, and the test still passes against cfdf4dc^ and
> against REL_11_STABLE.  I've queued a task to update the test code, but review
> can proceed in parallel.

Here's a version fixing that test for post-cfdf4dc backends.