From: David Steele <david@pgmasters.net>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: noah@leadboat.com
Cc: pgsql-hackers@postgresql.org
Cc: don@seiler.us
Subject: Re: Race between KeepFileRestoredFromArchive() and restartpoint
Date: Thu, 4 Aug 2022 06:32:38 -0400
Message-ID: <bd296352-77a6-2c46-5e3e-a548f74c2494@pgmasters.net> (raw)
In-Reply-To: <20220804.170640.1425291966829818860.horikyota.ntt@gmail.com>
References: <e1f1fb79-f668-0e7c-9841-763a023a7187@pgmasters.net>
<20220802143727.GA3796043@rfd.leadboat.com>
<20220804062456.GA3844351@rfd.leadboat.com>
<20220804.170640.1425291966829818860.horikyota.ntt@gmail.com>
On 8/4/22 04:06, Kyotaro Horiguchi wrote:
> At Wed, 3 Aug 2022 23:24:56 -0700, Noah Misch <noah@leadboat.com> wrote in
>>>> I think in this case a HINT might be sufficient to at least keep people from
>>>> wasting time tracking down a problem that has already been fixed.
>>
>> Here's a patch to add that HINT. I figure it's better to do this before next
>> week's minor releases. In the absence of objections, I'll push this around
>> 2022-08-05 14:00 UTC.
>
> +1
Looks good to me as well.
>>>> However, there is another issue [1] that might argue for a back patch if
>>>> this patch (as I believe) would fix the issue.
>>>
>>>> [1] https://www.postgresql.org/message-id/CAHJZqBDxWfcd53jm0bFttuqpK3jV2YKWx%3D4W7KxNB4zzt%2B%2BqFg%40ma...
>>>
>>> That makes sense. Each iteration of the restartpoint recycle loop has a 1/N
>>> chance of failing. Recovery adds >N files between restartpoints. Hence, the
>>> WAL directory grows without bound. Is that roughly the theory in mind?
>>
>> On further reflection, I don't expect it to happen that way. Each failure
>> message is LOG-level, so the remaining recycles still happen. (The race
>> condition can yield an ERROR under PreallocXlogFiles(), but recycling is
>> already done at that point.)
>
> I agree to this.
Hmmm, OK. We certainly have a fairly serious issue here, i.e. pg_wal
growing without bound. Even if we are not sure what is causing it, how
confident are we that the patches applied to v15 would fix it?
Regards,
-David
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: david@pgmasters.net, horikyota.ntt@gmail.com, noah@leadboat.com, don@seiler.us
Subject: Re: Race between KeepFileRestoredFromArchive() and restartpoint
In-Reply-To: <bd296352-77a6-2c46-5e3e-a548f74c2494@pgmasters.net>
* 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