Re: RFC: Logging plan of the running query

On Thu, Aug 17, 2023 at 10:02 AM torikoshia <torikoshia@oss.nttdata.com> wrote:
>
> On 2023-06-16 01:34, James Coleman wrote:
> > Attached is v28
> > which sets ProcessLogQueryPlanInterruptActive to false in errfinish
> > when necessary. Once built with those two patches I'm simply running
> > `make check`.
>
> With v28-0001 and v28-0002 patch, I confirmed backend processes consume
> huge
> amount of memory and under some environments they were terminated by OOM
> killer.
>
> This was because memory was allocated from existing memory contexts and
> they
> were not freed after ProcessLogQueryPlanInterrupt().
> Updated the patch to use dedicated memory context for
> ProcessLogQueryPlanInterrupt().
>
> Applying attached patch and v28-0002 patch, `make check` successfully
> completed after 20min and 50GB of logs on my environment.
>
> >>> On 2023-06-15 01:48, James Coleman wrote:
> >>> > The tests have been running since last night, but have been apparently
> >>> > hung now for many hours.
>
> I don't know if this has anything to do with the hung you faced, but I
> thought
> it might be possible that the large amount of memory usage resulted in
> swapping, which caused a significant delay in processing.

Ah, yes, I think that could be a possible explanation. I was delaying
on this thread because I wasn't comfortable with having caused an
issue once (even if I couldn't easily reproduce) without at least some
theory as to the cause (and a fix).

> If possible, I would be very grateful if you could try to reproduce this
> with
> the v29 patch.

I'll kick off some testing.

Thanks,
James Coleman