Re: [HACKERS] Reducing pg_ctl's reaction time

Andres Freund <andres@anarazel.de> writes:
> On 2017-06-26 17:30:30 -0400, Tom Lane wrote:
>> No, I don't like that at all.  Has race conditions against updates
>> coming from the startup process.

> You'd obviously have to take the appropriate locks.  I think the issue
> here is less race conditions, and more that architecturally we'd
> interact with shmem too much.

Uh, we are *not* taking any locks in the postmaster.

>> Yeah, that would be a different way to go at it.  The postmaster would
>> probably just write the state of the hot_standby GUC to the file, and
>> pg_ctl would have to infer things from there.

> I'd actually say we should just mirror the existing
> #ifdef USE_SYSTEMD
>         if (!EnableHotStandby)
>             sd_notify(0, "READY=1");
> #endif
> with corresponding pidfile updates - doesn't really seem necessary for
> pg_ctl to do more?

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.
        regards, tom lane