bug#61514: 30.0.50; sadistically long xml line hangs emacs

[Eli Zaretskii]

> Date: Tue, 21 Feb 2023 12:37:11 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: mah@everybody.org, 61514@debbugs.gnu.org, monnier@iro.umontreal.ca
> 
> 
> >
> > SGTM, but isn't 1000 a somewhat low value?  What if we use half of the 
> > value of long-line-optimizations-region-size instead?
> >
> 
> Here are some benchmarks.  The time taken by Emacs to open the 4 MB 
> "n_n_..." file with different regexps are:
> 
> "[^<>\n]\\{1,100\\}?\\<": 0.8 seconds
> "[^<>\n]\\{1,1000\\}?\\<": 3.4 seconds
> "[^<>\n]\\{1,10000\\}?\\<": 28.5 seconds
> "[^<>\n]\\{1,65535\\}?\\<": 162.9 seconds
> "[^<>\n]+?\\<": 356.6 seconds
> 
> 65535 is the upper limit for such ranges, it's not possible to use a 
> larger value.

OK, but does it sound outrageous to have more than 1K of non-newline
characters in a row without any brackets?

At the very least, maybe make the value be in some variable?