On June 29, 2017 10:19:46 AM PDT, Jeff Janes <jeff.janes@gmail.com> wrote:
>On Tue, Jun 27, 2017 at 11:59 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
>> I wrote:
>> > Andres Freund <andres@anarazel.de> writes:
>> >> On 2017-06-26 17:38:03 -0400, Tom Lane wrote:
>> >>> Hm. Take that a bit further, and we could drop the connection
>probes
>> >>> altogether --- just put the whole responsibility on the
>postmaster to
>> >>> show in the pidfile whether it's ready for connections or not.
>>
>> >> Yea, that seems quite appealing, both from an architectural,
>simplicity,
>> >> and log noise perspective. I wonder if there's some added
>reliability by
>> >> the connection probe though? Essentially wondering if it'd be
>worthwhile
>> >> to keep a single connection test at the end. I'm somewhat
>disinclined
>> >> though.
>>
>> > I agree --- part of the appeal of this idea is that there could be
>a net
>> > subtraction of code from pg_ctl. (I think it wouldn't have to link
>libpq
>> > anymore at all, though maybe I forgot something.) And you get rid
>of a
>> > bunch of can't-connect failure modes, eg kernel packet filter in
>the way,
>> > which probably outweighs any hypothetical reliability gain from
>> confirming
>> > the postmaster state the old way.
>>
>> Here's a draft patch for that. I quite like the results --- this
>seems
>> way simpler and more reliable than what pg_ctl has done up to now.
>> However, it's certainly arguable that this is too much change for an
>> optional post-beta patch.
>
>
>In the now-committed version of this, the 'pg_ctl start' returns
>successfully as soon as the server reaches a consistent state. Which is
>OK,
>except that it does the same thing when hot_standby=off. When
>hot_standby=off, I would expect it to wait for the end of recovery
>before
>exiting with a success code.
I've not looked at the committed version, but earlier versions had code dealing with that difference; essentially doing
whatyou suggest.
Andres
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