Re: BUG #14416: checkpoints never completed

Jonathon Nelson <jdnelson(at)dyn(dot)com> writes:
> On Mon, Nov 7, 2016 at 1:22 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I wonder if this is a problem similar to the autovacuum issue we fixed
>> in da1a9d0f5, ie perhaps moving the system clock setting confuses the
>> checkpoint timing logic.

> That is more or less what we were thinking as well.

Looking at the logic around this in checkpointer.c, it's pretty obvious
that it would not behave nicely if system time goes backwards after a
checkpoint starts; it would think it was ahead of schedule and would
just loaf, basically, until the clock catches up to where it had been.
There's no sanity check to notice a negative elapsed-time reading.
But if system time goes forwards, it would think it was very far behind
schedule and would do a burst of work, which doesn't seem to match your
symptom.

Please confirm the sign of the system clock correction that happened
on your machine?

regards, tom lane