Re: postgresql 8.4 semaphores ...

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

On 06/06/10 15:39, Malcolm Herbert wrote:
> On Sun, Jun 06, 2010 at 12:37:15PM +0200, Jean-Yves Migeon wrote:
> |On 06/06/10 10:39, Malcolm Herbert wrote:
> |>still, postgresql fails to start with an error complaining about semaphores 
> again (instead of memory):
> |>
> |>|FATAL:  could not create semaphores: No space left on device
> |>|DETAIL:  Failed system call was semget(31, 17, 03600).
> |>|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 (currently 13).
> |>
> |>starting to tear out my hair here ...
> |
> |Hmm, I don't think that the max number of sets or identifiers is the
> |problem here, but rather the maximum number of memory that could be
> |shared for locking. Do you still have ENOSPC when you increase
> |'kern.ipc.shmmaxpgs'?
>
> bumped that to 16384 (up from 4096) and still get the same error ... what would 
> be a suitable upper bound for this value?

It is already high enough; on my host, 40 max_connections, I have the 
following values:
# sysctl kern.ipc
kern.ipc.sysvmsg = 1
kern.ipc.sysvsem = 1
kern.ipc.sysvshm = 1
kern.ipc.shmmax = 8388608
kern.ipc.shmmni = 128
kern.ipc.shmseg = 128
kern.ipc.shmmaxpgs = 2048
kern.ipc.shm_use_phys = 0
kern.ipc.msgmni = 40
kern.ipc.msgseg = 2048
kern.ipc.semmni = 10
kern.ipc.semmns = 60
kern.ipc.semmnu = 30

For 8.4. Granted, the system is 5.1_RC, not -current.

Could you post the result of ipcs -b and ipcs -S, please?

--
Jean-Yves Migeon
jeanyves.migeon%free.fr@localhost