Subject: Re: Wait event that should be reported while waiting for WAL
 archiving to finish
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Haas <robertmhaas@gmail.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
References: <f0651f8c-9c96-9f29-0ff9-80414a15308a@oss.nttdata.com>
 <20200213032804.GB1520@paquier.xyz>
 <949931aa-4ed4-d867-a7b5-de9c02b2292b@oss.nttdata.com>
 <20200213073035.GI1520@paquier.xyz>
 <eb1287bd-64ee-07a5-057e-710d93e7f39e@oss.nttdata.com>
 <CA+Tgmoa3BVNJ+LVrytUrsK+MtxEogc_jurDgJ=rkMAEt06Hk6Q@mail.gmail.com>
 <61477660-dded-2550-b101-c76a2f864806@oss.nttdata.com>
 <20200217094857.GB115140@paquier.xyz>
From: Fujii Masao <masao.fujii@oss.nttdata.com>
Message-ID: <d9d85efa-f62e-400e-2edf-9e1b8c0df651@oss.nttdata.com>
Date: Mon, 17 Feb 2020 22:21:23 +0900
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On 2020/02/17 18:48, Michael Paquier wrote:
> On Mon, Feb 17, 2020 at 04:30:00PM +0900, Fujii Masao wrote:
>> On 2020/02/14 23:43, Robert Haas wrote:
>>> On Thu, Feb 13, 2020 at 10:47 PM Fujii Masao
>>> <masao.fujii@oss.nttdata.com> wrote:
>>>> Fixed. Thanks for the review!
>>>
>>> I think it would be safer to just report the wait event during
>>> pg_usleep(1000000L) rather than putting those calls around the whole
>>> loop. It does not seem impossible that ereport() or
>>> CHECK_FOR_INTERRUPTS() could do something that reports a wait event
>>> internally.
> 
> CHECK_FOR_INTERRUPTS() would reset the event wait state.  Hm..  You
> may be right about the WARNING and it would be better to not rely on
> that.  Do you remember the states which may be triggered?
> 
>> OK, so I attached the updated version of the patch.
>> Thanks for the review!
> 
> Actually, I have some questions:
> 1) Should a new wait event be added in recoveryPausesHere()?  That
> would be IMO useful.

Yes, it's useful, I think. But it's better to implement that
as a separate patch.

> 2) Perhaps those two points should be replaced with WaitLatch(), where
> we would use the new wait events introduced?

For what? Maybe it should, but I'm not sure it's worth the trouble.

Regards,

-- 
Fujii Masao
NTT DATA CORPORATION
Advanced Platform Technology Group
Research and Development Headquarters