Re: [HACKERS] Reducing pg_ctl's reaction time

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.