Re: BUG #17938: could not open shared memory segment "/PostgreSQL.615216676": No such file or directory

At Tue, 23 May 2023 07:43:11 +0900, Michael Paquier <michael@paquier.xyz> wrote in 
> On Mon, May 22, 2023 at 06:10:43PM +0000, PG Bug reporting form wrote:
> > The server does not run any systemd but is pure Init-V.  So it is very
> > unlikely that a systemd process causes this.Also no container in use. Init
> > process directly runs postgres server. Kernel is 5.15.80 and was the same
> > for version 14. I also don't log in with the postgres-user which is also
> > impossible (disabled in /etc/shadow). WIthin 7 days this happens very
> > likely/ at least once. How can I track this down further?> 
> 
> Are you sure that your system does not run systemd and enable
> RemoveIPC?  Even if the PostgreSQL service is not running with it, you
> would be able to see see issue as long as the parameter is enabled:
> https://www.postgresql.org/message-id/BACA8550-4F3D-41D0-A0E1-5BF307BCD648@elevated-dev.com

The OP says:
> I don't use shared_memory_type and also not dynamic_shared_memory_type so
> they're default (mmap for the first, posix for the second). Got the settings

It looks like the OP might be misunderstanding
dynamic_shared_memory_type. Outside of Windows, it first prefers
posix, then sysv and finally mmap. Thus it is quite usual to use posix
for DSM segments. Actually posix is defaultly used for
dynamic_shared_memory_type on my Rocky 9 box.

I can't pinpoint why the "No such file or directory" is comnig up,
though.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center