Re: Default of jit-lock-stealth-time

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Sure, but there's little incentive to do so, so the rather heavy-handed
> way you jumped on Eli seems out of place.

Sorry, I guess it sounded louder than I intended.

> The implication seemed to be that if he didn't "observe some benefit",
> then there likely wasn't any (which obviously isn't true).

We're just trying to find people who have observed benefits.  It looks
like Eli isn't one of them.  Maybe there are such people, but I expect
they're very rare:

I've played a good bit with jit-lock (while working on its code, on
syntax-ppss, and on various major mode's font-lock patterns), using
a relatively modest machine at the time (about 4 years old, but
top-of-the-line when new) running on an Emacs compiled with all known
runtime checks.  I've seen significant delays with jit-lock under some
specific circumstances, and in those circumstances jit-lock-stealth was able
to reduce the occurrence of those cases, but it never seemed enough: the
remaining cases were still too severe.  So in practice I expect every major
mode's font-lock rules to be tuned by the author to avoid such
circumstances, such that jit-lock is fast enough and jit-lock-stealth never
makes a noticeable difference.

>> We know fairly well about the downsides and we know they don't affect
>> everybody all the time, so this is not the interesting part of
>> the discussion.

> It serves to put the strident opposition to stealth fontification in
> context, I think.

Sure.  Jit-lock-stealth has been in wide use since Emacs-21.1 (and the years
of development before), so it's clear that its bad effects are
sufficiently mild.


        Stefan