I committed this change. I also did some more research and this change
in PostgreSQL 18 is deliberate:
https://github.com/postgres/postgres/commit/810a8b1c8051d4e8822967a96f133692698386de
Jeremy
On 12/05 06:43, Jeremy Evans wrote:
> I received a report that the default semmns limit is no longer sufficient
> to start PostgreSQL. Instead of reducing the number of max connections,
> it just will not start. Here's the initdb output you get with the default
> limits:
>
>
> running bootstrap script ... 2025-12-05 18:41:22.252 PST [50524] FATAL: could
> not create semaphores: No space left on device
> 2025-12-05 18:41:22.252 PST [50524] DETAIL: Failed system call was
> semget(311051, 17, 03600).
> 2025-12-05 18:41:22.252 PST [50524] HINT: This error does *not* mean that
> you have run out of disk space. It occurs when either the system limit for
> the maximum number of semaphore sets (SEMMNI), or the system wide maximum
> number of semaphores (SEMMNS), would be exceeded. You need to raise the
> respective kernel parameter. Alternatively, reduce PostgreSQL's consumption
> of semaphores by reducing its "max_connections" parameter.
> The PostgreSQL documentation contains more information about
> configuring your system for PostgreSQL.
> child process exited with exit code 1
> initdb: removing contents of data directory "/var/postgresql/data"
>
>
> The postgresql-server pkg README has recommended these limits for a
> long time:
>
> kern.seminfo.semmni=256
> kern.seminfo.semmns=2048
>
> I think we should adjust the text of the README to reflect the
> behavior change starting in PostgreSQL 18.
>
> OKs?
>
> Thanks,
> Jeremy
>
> Index: Makefile
> ===================================================================
> RCS file: /cvs/ports/databases/postgresql/Makefile,v
> retrieving revision 1.314
> diff -u -p -u -p -r1.314 Makefile
> --- Makefile 23 Nov 2025 03:05:13 -0000 1.314
> +++ Makefile 6 Dec 2025 02:35:03 -0000
> @@ -9,6 +9,7 @@ VERSION= 18.1
> PREV_MAJOR= 17
> DISTNAME= postgresql-${VERSION}
> PKGNAME-main= postgresql-client-${VERSION}
> +REVISION-server=0
>
> DPB_PROPERTIES= parallel
>
> Index: pkg/README-server
> ===================================================================
> RCS file: /cvs/ports/databases/postgresql/pkg/README-server,v
> retrieving revision 1.37
> diff -u -p -u -p -r1.37 README-server
> --- pkg/README-server 1 Jun 2024 05:36:58 -0000 1.37
> +++ pkg/README-server 6 Dec 2025 02:35:03 -0000
> @@ -57,17 +57,19 @@ Restart PostgreSQL to allow these change
> Tuning for busy servers
> =======================
> The default sizes in the GENERIC kernel for SysV semaphores are not
> -large enough for PostgreSQL to use the default max_connections
> -configuration value of 100, so PostgreSQL will use a smaller than
> -default max_connections if you do not increase the limits. Adding the
> -following in /etc/sysctl.conf will be reasonable for many systems:
> +large enough for PostgreSQL. Adding the following in /etc/sysctl.conf
> +should allow PostgreSQL to start:
>
> kern.seminfo.semmni=256
> kern.seminfo.semmns=2048
>
> +While you can start PostgreSQL with smaller limits, it's probably
> +not wise unless you are very resource constrained.
> +
> You may also want to tune the max_connections value in the
> postgresql.conf file to increase the number of connections to the
> -backend.
> +backend. However, for busy servers with many connections, these
> +limits may need to be increased further.
>
> By default, the _postgresql user, and so the postmaster and backend
> processes run in the login(1) class of "postgresql". On a busy server,
> @@ -77,10 +79,6 @@ more memory, etc.
>
> The capability database file is located at /etc/login.conf.d/postgresql
>
> -For more than about 250 connections, these numbers should be
> -increased. Please report any changes and experiences to the package
> -maintainers so that we can update this file for future versions.
> -
> Upgrade Howto (for a major upgrade)
> ===================================
> If you didn't install PostgreSQL by following this README,
