Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

On Wed, Mar 13, 2024 at 12:01 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2024-Mar-13, Jelte Fennema-Nio wrote:
> > Sadly I'm having a hard time reliably reproducing this race condition
> > locally. So it's hard to be sure what is happening here. Attached is a
> > patch with a wild guess as to what the issue might be (i.e. seeing an
> > outdated "active" state and thus passing the check even though the
> > query is not running yet)
>
> I tried leaving the original running in my laptop to see if I could
> reproduce it, but got no hits ... and we didn't get any other failures
> apart from the three ones already reported ... so it's not terribly high
> probability.  Anyway I pushed your patch now since the theory seems
> plausible; let's see if we still get the issue to reproduce.  If it
> does, we could make the script more verbose to hunt for further clues.

I hit this on my machine. With the attached diff I can reproduce
constantly (including with the most recent test patch); I think the
cancel must be arriving between the bind/execute steps?

Thanks,
--Jacob