pg.ddx.io  pgsql-hackers@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Cc: tsunakawa.takay@fujitsu.com <tsunakawa.takay@fujitsu.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: SLRU statistics
Date: Wed, 13 May 2020 17:28:46 +0200
Message-ID: <20200513152846.goee2c5xrly52ga2@development> (raw)
In-Reply-To: <fe3332c8-485a-540b-ca34-b024d452a7ae@oss.nttdata.com>
References: <20200502000818.nn4kpewiput42bnb@development>
	<49b8ad17-f6d9-a086-a952-ff1fec3ac1b3@oss.nttdata.com>
	<20200502105500.hwhba3d6s3hlrqf6@development>
	<20200502165905.brfxv6dk5vjdbgti@development>
	<976bbb73-a112-de3c-c488-b34b64609793@oss.nttdata.com>
	<b8784fe6-1401-ab35-aa14-d57b5bb8e312@oss.nttdata.com>
	<20200513082159.myflgcs5fnhnujbk@development>
	<b407746a-4fb6-7128-9391-c3765eb44718@oss.nttdata.com>
	<32135.1589379999@sss.pgh.pa.us>
	<fe3332c8-485a-540b-ca34-b024d452a7ae@oss.nttdata.com>

On Wed, May 13, 2020 at 11:46:30PM +0900, Fujii Masao wrote:
>
>
>On 2020/05/13 23:26, Tom Lane wrote:
>>Fujii Masao <masao.fujii@oss.nttdata.com> writes:
>>>On 2020/05/13 17:21, Tomas Vondra wrote:
>>>>On Wed, May 13, 2020 at 04:10:30PM +0900, Fujii Masao wrote:
>>>>>Also I found another minor issue; SLRUStats has not been initialized to 0
>>>>>and which could update the counters unexpectedly. Attached patch fixes
>>>>>this issue.
>>
>>>Pushed both. Thanks!
>>
>>Why is that necessary?  A static variable is defined by C to start off
>>as zeroes.
>
>Because SLRUStats is not a static variable. No?
>

I think it counts as a variable with "static storage duration" per 6.7.8
(para 10), see [1]. I wasn't aware of this either, but it probably means
the memset is unnecessary.

Also, it seems a bit strange/confusing to handle this differently from
BgWriterStats. And that worked fine without the init for years ...


[1] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

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





view thread (49+ messages)  latest in thread

Message-ID: <20200513152846.goee2c5xrly52ga2@development>
Permalink:  ../20200513152846.goee2c5xrly52ga2@development/
Also on:    postgresql.org/message-id/20200513152846.goee2c5xrly52ga2@development

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-hackers@postgresql.org
  Cc: tomas.vondra@2ndquadrant.com, masao.fujii@oss.nttdata.com, tgl@sss.pgh.pa.us, alvherre@2ndquadrant.com, masahiko.sawada@2ndquadrant.com, tsunakawa.takay@fujitsu.com
  Subject: Re: SLRU statistics
  In-Reply-To: <20200513152846.goee2c5xrly52ga2@development>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox