From: Tom Lane <tgl@sss.pgh.pa.us>
To: frank picabia <fpicabia@gmail.com>
cc: pgsql-admin@postgresql.org
Subject: Re: Error: "could not fork new process for connection: Cannot
 allocate memory"
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Comments: In-reply-to frank picabia <fpicabia@gmail.com>
	message dated "Mon, 21 Dec 2020 21:13:39 -0400"
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Date: Mon, 21 Dec 2020 20:27:43 -0500
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frank picabia <fpicabia@gmail.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