Re: Dangerous hint in the PostgreSQL manual

Listaccount wrote:
> Yes, but the documentation should at least warn if some setting
> *could* lead to trouble you would not have otherwise.
>
> > What I _would_ support in the docs is the following addition in 17.4.3,
> > where this is discussed:
> >
> > . . .it will lower the chances significantly and will therefore
> > lead to more robust system behavior. It may also cause fork() to fail
> > when the machine appears to have available memory. This is done by
> > selecting. . .
> >
> > Or something like that. This would warn potential users that they really do
> > need to read their kernel docs.
>
> On this one we can agree. Maybe we should mention the root-cause.
>
> "It may also cause fork() to fail when the machine appears to have
> available memory because of other applications doing careless memory
> allocation"
>
> Would be nice to save others from learning about this the hard way.

Good, text added in parentheses:

On Linux 2.6 and later, an additional measure is to modify the
kernel's behavior so that it will not <quote>overcommit</> memory.
Although this setting will not prevent the OOM killer from
invoking altogether, it will lower the chances significantly and
will therefore lead to more robust system behavior. (It might also
cause fork() to fail when the machine appears to have available memory
because of other applications with careless memory allocation.) This
is done by selecting strict overcommit mode via

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +