Subject: Re: ERROR: invalid spinlock number: 0
To: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>, Thomas Munro
 <thomas.munro@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
References: <7ef8708c-5b6b-edd3-2cf2-7783f1c7c175@oss.nttdata.com>
 <YCUpTL8bZHa+9K+0@paquier.xyz>
 <79698f73-7dd7-d9e3-5322-4032b4428653@oss.nttdata.com>
 <YCowabyl1dwan+JP@paquier.xyz>
 <CA+hUKG+tZHpADD_BsPp=c3EiYeenTTx5AxsZVGkv1mA0J3O21w@mail.gmail.com>
 <YCpQwdyXErcTRhVX@paquier.xyz>
 <20210215212805.dfahbpqqpnl6lgwm@alap3.anarazel.de>
 <918a47fc-e1fa-0c99-15e3-59b520455fe0@oss.nttdata.com>
 <YCtrN5BgwK9JuQyd@paquier.xyz>
 <efca765d-a523-dd5d-549d-04f8d76837ac@oss.nttdata.com>
 <YCyg+XrLMcYWpNOT@paquier.xyz>
From: Fujii Masao <masao.fujii@oss.nttdata.com>
Message-ID: <d1325f62-16f3-9cee-9ca1-8e2626e17b29@oss.nttdata.com>
Date: Thu, 18 Feb 2021 23:32:16 +0900
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0)
 Gecko/20100101 Thunderbird/78.7.1
MIME-Version: 1.0
In-Reply-To: <YCyg+XrLMcYWpNOT@paquier.xyz>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 2021/02/17 13:52, Michael Paquier wrote:
> On Tue, Feb 16, 2021 at 11:47:52PM +0900, Fujii Masao wrote:
>> On 2021/02/16 15:50, Michael Paquier wrote:
>>> +   /*
>>> +    * Read "writtenUpto" without holding a spinlock. So it may not be
>>> +    * consistent with other WAL receiver's shared variables protected by a
>>> +    * spinlock. This is OK because that variable is used only for
>>> +    * informational purpose and should not be used for data integrity checks.
>>> +    */
>>> What about the following?
>>> "Read "writtenUpto" without holding a spinlock.  Note that it may not
>>> be consistent with the other shared variables of the WAL receiver
>>> protected by a spinlock, but this should not be used for data
>>> integrity checks."
>>
>> Sounds good. Attached is the updated version of the patch.
> 
> Thanks, looks good to me.

Pushed. Thanks!


> 
>>> I agree that what has been done with MyProc->waitStart in 46d6e5f is
>>> not safe, and that initialization should happen once at postmaster
>>> startup, with a write(0) when starting the backend.  There are two of
>>> them in proc.c, one in twophase.c.  Do you mind if I add an open item
>>> for this one?
>>
>> Yeah, please feel free to do that! BTW, I already posted the patch
>> addressing that issue, at [1].
> 
> Okay, item added with a link to the original thread.

Thanks!

Regards,


-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION