Re: warn-maybe-out-of-memory

[Dmitry Antipov]

On 07/12/2014 09:17 PM, Glenn Morris wrote:

> > Here's another problem: what kind of "free memory" do you measure?

"Free" means "immediately available for allocation", i.e. not used by
OS or other processes for any purpose. If an OS should perform some
non-trivial action to get more memory (increase swap space or shrink
some internal data structures), this is not accounted as "free".

> I'd also like to know. If it really is the 8G amount in the example
> above, then as you say that seems just plain wrong for Emacs to warn
> about.

In the example above, I asked for 10G having just 8G free. In that example,
OS was able to shrink page cache by 2GB and satisfy the request; but we
can't assume that OS succeeds with this each time we ask to allocate a lot
of memory.

> Because who is opening a file with Emacs that matches the
> amount of RAM on their machine?

This is not uncommon editing task: as Google reports, users asks this question
after unsuccessful attempts to use their standard/favorite editors. For example:
http://askubuntu.com/questions/28847/text-editor-to-edit-4-3-gb-plain-text-file.

> The performance of Emacs is pretty poor with large files - the default
> large-file-warning-threshold is 10MB!

This may be subject to change without notice :-).

Dmitry