Re: [HACKERS] postmaster failure with 2-23 snapshot

Tom Ivar Helbekkmo <tih(at)nhh(dot)no> writes:
> Looking more closely into it, the postmaster is trying to allocate 64
> semaphores in four groups of 16, so I built a new kernel with a higher
> limit, and it's now OK.
> This is as it should be, I hope? It's not a case of something being
> misconfigured now, using semaphores instead of some other facility?

Yes, this is an intentional change --- I guess you haven't been reading
the hackers list very closely. The postmaster is now set up to grab
all the semaphores Postgres could need (for the specified number of
backend processes) immediately at postmaster startup. Failing then
for lack of semaphores seems a better idea than failing under load
when you try to start the N+1'st client, which is what used to happen.

There has been some discussion of reducing the default number-of-
backends limit to 32 so that a stock installation is less likely
to run out of semaphores.

regards, tom lane