Feedback-ID: ie3de48e3:Fastmail
Date: Fri, 19 Jun 2026 16:01:47 +0200
From: =?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: fix pg_mkdir_p to tolerate concurrent directory creation
Message-ID: <ajVLauHFakqDsXsY@alvherre.pgsql>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <3ca004de-e49b-4471-b8aa-fd656e70f68c@dunslane.net>
Archived-At: 
 <https://www.postgresql.org/message-id/ajVLauHFakqDsXsY%40alvherre.pgsql>
Precedence: bulk

On 2026-Jun-18, Andrew Dunstan wrote:

> 
> While working on the pytest stuff, I found this issue when making it work on
> Windows, but the issue can exist everywhere. pg_mkdir_p can fail if there is
> a concurrent directory creation. This patch makes it tolerant of concurrent
> directory creation.

Hmm, should the 'break's in the loop be 'continue's?  If you're creating
path a/b/c, and a concurrent process beats you but is only attempting to
do a/b, then with the break you'll fail to create the final c.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
Bob [Floyd] used to say that he was planning to get a Ph.D. by the "green
stamp method," namely by saving envelopes addressed to him as 'Dr. Floyd'.
After collecting 500 such letters, he mused, a university somewhere in
Arizona would probably grant him a degree.              (Don Knuth)