Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Alan Mackenzie <acm@muc.de> writes:
>
>> I more wonder why those limits are so low.  It's a long time since PCs'
>> RAM capacity was measured in mere megabytes.
>
> That, and then the fact that I can produce very long undo list, as long
> as they don't exceed the size in bytes limits. And these lists can
> contain a lot of markers.
>
> (defun my-test-undo-list ()
>   (interactive)
>   (with-current-buffer (get-buffer-create "undo-list-test.txt")
>     (erase-buffer)
>     (setf buffer-undo-list nil)
>     (dotimes (i 1000)
>       (dotimes (j 10)
> 	(insert "abcd")
> 	(dotimes (i 5) (point-marker))
> 	(backward-delete-char 1)
> 	(undo-boundary)
> 	(insert "\n")))
>     '(igc-collect)
>     (message "undo-list length %d (%d)" (length buffer-undo-list) n-compacted)
>     '(kill-buffer (current-buffer))))
>
> The above produces an undo list with length 80000.
>
> I think it might make sense to limit that to some reasonable number.

@Oscar: the patch below adds such a variable. My gut feeling is that
might well resolve the whole problem, without the other stuff, i.e.
applied directly to feature/igc. Sorry for the back and forth.