Re: Parallel query hangs after a smart shutdown is issued

Thomas Munro <thomas.munro@gmail.com> writes:
> On Fri, Aug 14, 2020 at 4:45 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> After some more rethinking and testing, here's a v5 that feels
>> fairly final to me.  I realized that the logic in canAcceptConnections
>> was kind of backwards: it's better to check the main pmState restrictions
>> first and then the smart-shutdown restrictions afterwards.

> LGTM.  I tested this a bit today and it did what I expected for
> parallel queries and vacuum, on primary and standby.

Thanks for reviewing!  I'll do the back-patching and push this today.

>> I'm assuming we want to back-patch this as far as 9.6, where parallel
>> query began to be a thing.

> Yeah.  I mean, it's more radical than what I thought we'd be doing for
> this, but you could get into real trouble by running in smart shutdown
> mode without the autovac infrastructure alive.

Right.  99.99% of the time, that early shutdown doesn't really cause
any problems, which is how we've gotten away with it this long.  But if
someone did leave session(s) running for a long time after issuing the
SIGTERM, the results could be bad --- and there's no obvious benefit
to the early shutdowns anyway.

            regards, tom lane