Hi Francisco,
Thank you for your advice. I used "ipcs" to get more readable information about the shared memory:
# ipcs -m -l --human
------ Shared Memory Limits --------
max number of segments = 4096
max seg size = 16E
max total shared memory = 16E
min seg size = 1B
# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x04000194 35 postgres 600 56 19
# ipcs -m -i 35
Shared memory Segment shmid=35
uid=26 gid=26 cuid=26 cgid=26
mode=0600 access_perms=0600
bytes=56 lpid=7653 cpid=3875 nattch=19
att_time=Tue May 28 22:56:35 2024
det_time=Tue May 28 22:56:35 2024
change_time=Tue May 28 07:59:59 2024
As far as I understand, there is no upper limit to the size of the shared memory. The database only holds a single
sharedmemory segment, which doesn't seem to have a relevant size.
I am surprised to see this since I would have expected much more shared memory to be used by the database. Is there
anythingin the configuration that prevents the shared memory from being used?
Best,
Christian
-----Original Message-----
From: Francisco Olarte <folarte@peoplecall.com>
Sent: Tuesday, May 28, 2024 7:15 PM
To: Christian Schröder <christian.schroeder@wsd.com>
Cc: pgsql-general@lists.postgresql.org; Eric Wong <eric.wong@wsd.com>
Subject: Re: Memory issues with PostgreSQL 15
[EXTERNAL]
Hi Christian:
On Tue, 28 May 2024 at 18:40, Christian Schröder <christian.schroeder@wsd.com> wrote:
> <2024-05-21 11:34:46 CEST - mailprocessor> ERROR: could not resize
> shared memory segment "/PostgreSQL.2448337832" to 182656 bytes: No
> space left on device
This hints at some shm function getting an ENOSPC: Coupled with...
> I thought this could all be related to our "shared_buffers" setting, so I increased it to 8 GB. This almost
immediately(after a few minutes) gave me these errors:
A faster fail when increasing it I would start by checking your IPC shared memory limits are ok, especially if you
upgradedsomething in the OS when going from 9 to 15, which seems likely.
IIRC in linux you can read them in /proc/sys/kernel/shm*, and they were configured via sysctl.
Francisco Olarte.
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