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

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David Rader
davidr(at)openscg(dot)com

On Tue, Feb 14, 2017 at 5:28 AM, Nikolai Zhubr <n-a-zhubr(at)yandex(dot)ru> wrote:

> 14.02.2017 12:47, John R Pierce:
>
>> On 2/13/2017 11:03 PM, Nikolai Zhubr wrote:
>>
>>> Now I'd like to locate a CPU eater more precisely - supposedly there
>>> is some issue with communication, that is why I don't want to mix in
>>> anything else.
>>>
>>
>> use iperf to test the network transport layer, without any postgres in
>> the loop?
>>
>
> No, the network performance in general is fine. However, some specific
> continuous communication pattern causes something to go very wrong on
> windows periodically. (And there is no such problem on linux btw) While the
> issue now seems rather related to windows itself and not postgres, but the
> pattern typical for some of my postgres uses is apparently a reliable
> trigger. Therefore, I'm thinking to first isolate the problem inside
> postgres, and if it still triggers then, second step, create a test
> "server" consisting of communication code of postgres to run without any
> other parts of postgres.
>
>
> Regards,
> Nikolai
>
>
>
>>
>>
>
Try the libpq call from pg_isready. It does actually make a round trip to
the postgres server and asks the server if it is ready to accept
connections. So you are running the socket communication code of postgres
and a small bit of "status" check but not any sql.

from mirror:
https://github.com/postgres/postgres/blob/master/src/bin/scripts/pg_isready.c

relevant call is PQping:

rv = PQpingParams(keywords, values, 1);