bug#28945: 25.2; desktop auto save timer does not work

[Peter Neidhardt <pe.neidhardt@googlemail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> > What this boils down to is that every automatic desktop-save produces
>> > an annoying "hiccup" in Emacs responsiveness.
>>
>> It's an idle timer, so if Emacs is idle, i.e. the user does not do
>> anything, how to you notice the hiccup?
>
> I notice it when I resume typing during the time desktop.el
> auto-saves.  The response to my typing is "sluggish", because once the
> timer function starts running, it runs to completion, before Emacs
> notices I typed something and responds.

Correct me if I'm wrong:

- If you keep using Emacs for hours (that is "typing/moving the point
  around") without taking a 30 sec break, then the timer won't trigger
  the desktop saving.  Right?

- The sluggishness would only be noticed if you happen to do nothing for
  more than `desktop-auto-save-timeout' but for less than
  desktop-auto-save-timeout + "time needed for saving".  It seems
  improbable that this happens _often_.

- I've used desktop-mode for years and I've never noticed any
  sluggishness as it takes less than a fraction of a second to save.
  I've had crappy computers, but admitedly most of them had an SSD.  My
  current timeout is 5 and I don't see any performance impact even on a
  bad computer with an even worse HDD.

Either way, the default value is not that important since every user is free
to change the value.  What is more important is to document it
properly.  Something in the line of:

> If you experience any irresponsiveness everytime desktop gets saved,
> increase the timeout.
> If not, it's safe to have it around 10.

What do you think?

Cheers!

--
Peter Neidhardt

The difference between legal separation and divorce is that legal
separation gives the man time to hide his money.