Re: Error: "could not fork new process for connection: Cannot allocate memory"

Thanks for the responses.

We'll take this up with VMware support and then if it isn't a
configuration issue, move it along to Redhat Linux support.

It was also useful to learn cgroups default support within the kernel can
use up so much memory on a system with larger RAM. On the next reboot this
will free up about 1.6 GB RAM. It might help with a little wiggle room
until we know more about the other issue which seems to limit us to 1/2 our
RAM.

On Mon, Dec 21, 2020 at 9:27 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> frank picabia <fpicabia(at)gmail(dot)com> writes:
> > My VMware admin has come back with a graph showing memory use over
> > the period in question. He has looked over other indicators
> > and there are no alarms triggered on the system.
> > It jives with what Cacti reported. Memory was never exhausted
> > and used only 50% of allocated RAM at the most.
>
> > If it's not a configuration issue in Postgres, and both internal and
> > external tools
> > show memory was not consumed to the point of firing off the "cannot fork"
> > error, would that mean that there is a bug in either the kernel or
> Postgres?
>
> [ shrug... ] Postgres is just reporting to you that the kernel wouldn't
> perform a fork(). Since you've gone to great lengths to show that
> Postgres isn't consuming excessive resources, either this is a kernel bug
> or you're running into some kernel-level (not Postgres) allocation limit.
> I continue to suspect the latter. Desultory googling shows that VMware
> can be configured to enforce resource allocation limits, so maybe you
> should be taking a hard look at your VMware settings.
>
> regards, tom lane
>