Re: Postgresql 7.3 on Red Hat Enterprise 5 (Problem with SEMMNI, SEMMNS)

Darek Czarkowski <dczarkowski(at)infinitesource(dot)ca> writes:
> I am have installed postgresql-7.3.4 on Linux server running Red Hat Enterp=
> rise Linux Server release 5 (Tikanga).

Why in heavens name would you be wanting to run 7.3.4? Even if you have
a good reason for wanting 7.3.x, you should be installing 7.3.19. We
don't update back branches just because we have nothing better to do.
Read the release notes starting here:
http://developer.postgresql.org/pgdocs/postgres/release-7-3-19.html
and then get onto a more recent version.

> Postmaster runs fine with the default settings, but when I try to increase =
> number of connections to 200 I get
> "IpcSemaphoreCreate: semget(key=5432120, num=17, 03600) failed: No spac=
> e left on device" Error

Hmm ... I suppose you are hitting the SEMMNI limit, but unless there is
something else eating semaphores in the system, you should be able to go
way higher than that with the default Red Hat settings. (I can run more
than 2000 connections without changing the defaults on a Fedora 6
machine.)

What I suspect is that there is something you didn't tell us about this
machine, like that it's not a vanilla x86-architecture machine, and that
PG 7.3.4 doesn't have any spinlock code for it. In that case your build
would have fallen back to using semaphores for spinlocks, which aside
from being horrendously slow eats many more semaphores than normal (I
think two per shared buffer, for one thing). In this connection it is
worth pointing to the 7.3.16 release notes ...

regards, tom lane