Subject: Re: shared-memory based stats collector
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
 Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, ah@cybertec.at,
 magnus@hagander.net, robertmhaas@gmail.com, tgl@sss.pgh.pa.us,
 pgsql-hackers@postgresql.org
References: <20181129121819.5vgq7fuohkheq7wu@alvherre.pgsql>
 <854d6d91-f2f3-e391-f0fc-064db51b391e@2ndquadrant.com>
 <20190101180318.xikb6b4nm57pjtju@alap3.anarazel.de>
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <54232a9d-0bba-2bc2-6ed2-70598372459c@2ndquadrant.com>
Date: Tue, 1 Jan 2019 20:14:25 +0100
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On 1/1/19 7:03 PM, Andres Freund wrote:
> Hi,
> 
> On 2019-01-01 18:39:12 +0100, Tomas Vondra wrote:
>> On 11/29/18 1:18 PM, Alvaro Herrera wrote:
>>> On 2018-Nov-28, Tomas Vondra wrote:
>>>
>>>>> v10-0004-Shared-memory-based-stats-collector.patch
>>>>>   updated not to touch guc.
>>>>> v10-0005-Remove-the-GUC-stats_temp_directory.patch
>>>>>   collected all guc-related changes.
>>>>>   updated not to break other programs.
>>>>> v10-0006-Split-out-backend-status-monitor-part-from-pgstat.patch
>>>>>   basebackup.c requires both bestats.h and pgstat.h
>>>>> v10-0007-Documentation-update.patch
>>>>>   small change related to 0005.
>>>>
>>>> I need to do a more thorough review of part 0006, but these patches
>>>> seems quite fine to me. I'd however merge 0007 into the other relevant
>>>> parts (it seems like a mix of docs changes for 0004, 0005 and 0006).
>>>
>>> Looking at 0001 - 0003 it seems OK to keep each as separate commits, but
>>> I suggest to have 0004+0006 be a single commit, mostly because
>>> introducing a bunch of "new" code in 0004 and then moving it over to
>>> bestatus.c in 0006 makes "git blame" doubly painful.  And I think
>>> committing 0005 and not 0007 makes the documentation temporarily buggy,
>>> so I see no reason to think of this as two commits, one being 0004+0006
>>> and the other 0005+0007.  And even those could conceivably be pushed
>>> together instead of as a single patch.  (But be sure to push very early
>>> in your work day, to have plenty of time to deal with any resulting
>>> buildfarm problems.)
>>>
>>
>> Kyotaro-san, do you agree with committing the patch the way Alvaro
>> proposed? That is, 0001-0003 as separate commits, and 0004+0006 and
>> 0005+0007 together. The plan seems reasonable to me.
> 
> Do you guys think these patches are ready already? I'm a bit doubtful, and
> failures here could have quite wide-ranging symptoms.
> 

I agree it's a sensitive part of the code, so additional reviews would
be welcome of course. I've done as much review and testing as possible,
and overall it seems in a fairly good shape. Do you have any particular
concerns / ideas what to look for?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services