Re: pg_basebackup may fail to send feedbacks.

On Wed, Feb 18, 2015 at 5:34 PM, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> Hello, this is the last patch for pg_basebackup/pg_receivexlog on
> master (9.5). Preor versions don't have this issue.
>
> 4. basebackup_reply_fix_mst_v2.patch
> receivelog.c patch applyable on master.
>
> This is based on the same design with
> walrcv_reply_fix_91_v2.patch in the aspect of gettimeofday().

Thanks for updating the patches! But I'm still not sure if the idea depending
on the frequent calls of gettimeofday() for each WAL receive is good or not.
Some users may complain about the performance impact by such frequent calls
and we may want to get rid of them from walreceiver loop in the future.
If we adopt your idea now, I'm afraid that it would tie our hands in that case.

How much impact can such frequent calls of gettimeofday() have on replication
performance? If it's not negligible, probably we should remove them at first
and find out another idea to fix the problem you pointed. ISTM that it's not so
difficult to remove them. Thought? Do you have any numbers which can prove
that such frequent gettimeofday() has only ignorable impact on the performance?

Regards,

--
Fujii Masao