Re: Causeless CPU load waves in backend, on windows, 9.5.5 (EDB binary).

On Mon, Jan 30, 2017 at 6:16 PM, Nikolai Zhubr <n-a-zhubr(at)yandex(dot)ru> wrote:
> I'm observing some strange inexplicable effect in 9.5.5 server running on
> x86 windows (32-bit windows xp sp3).

Oh, well... You are aware that this is out of support by Microsoft, right?

> That is, CPU usage in backend process
> for the session in question starts to grow, going from approx 0-1 to 8-15
> percent and more, stays that high for several seconds, then goes back to
> 0-1. All the effect takes about 15-30 seconds, and repeats stably every
> 10-20 minutes (as long as the respective client continues to run the same
> queries). Apparently it is essential to consider the pattern of requests
> going to the server: in this case there is a continuous stream of very small
> cheap queries, but quite a lot of them per second. Trying to understand the
> reason, I've managed to craft a pure artifical test triggering very similar
> CPU load waves without the need for any specific database at all, easy to
> repeat:
>
> 1. "select localtimestamp" 40 times (As separate requests, one by one, but
> no delay inserted in between)
> 2. wait 1/2 second.
> 3. goto 1

Craig, could this be a side-effect of 519b0757? That's new in 9.5, and
that's directly related to the code paths discussed here.
--
Michael