Re: Restart pg_usleep when interrupted

Hi,

On Thu, Jul 11, 2024 at 10:15:41AM -0500, Sami Imseih wrote:
>
> > I did a few tests with the patch and did not see any "large" drifts like the
> > ones observed above.
>
> Thanks for testing.
>
> > I think it could be "simplified" by making use of instr_time instead of timespec
> > for current and absolute. Then I think it would be enough to compare their
> > ticks.
>
> Correct I attached a v2 of this patch that uses instr_time to check the elapsed
> time and break out of the loop. It needs some more benchmarking.

Thanks!

Outside of Nathan's comment:

1 ===

+ * However, since nanosleep is susceptible to time drift when interrupted
+ * frequently, we add a safeguard to break out of the nanosleep whenever the

I'm not sure that "nanosleep is susceptible to time drift when interrupted frequently"
is a correct wording.

What about?

"
However, since the time between frequent interruptions and restarts of the
nanosleep calls can substantially lead to drift in the time when the sleep
finally completes, we add...."

2 ===

+static void vacuum_sleep(double msec);

What about a more generic name that could be used outside of vacuum?

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com