GNU bug report logs - #56682
Fix the long lines font locking related slowdowns

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Package: emacs;

Reported by: Gregory Heytings <gregory <at> heytings.org>

Date: Thu, 21 Jul 2022 18:01:01 UTC

Severity: normal

Done: Gregory Heytings <gregory <at> heytings.org>

Bug is archived. No further changes may be made.

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Message #1018 received at 56682 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Gregory Heytings <gregory <at> heytings.org>
Cc: 56682 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>,
 monnier <at> iro.umontreal.ca
Subject: Re: bug#56682: Fix the long lines font locking related slowdowns
Date: Fri, 5 Aug 2022 15:28:55 +0300
On 04.08.2022 04:41, Gregory Heytings wrote:
> 
>>
>> We cannot perform every basic operation in fixed time for any 
>> arbitrarily sized file. There are limits of what we can possibly do.
>>
> 
> Apparently the limits are lower than what you think.  Provided that we 
> accept some compromises, such as mis-fontification, which is also what 
> syntax-wholeline-max does, and against which you didn't protest.

syntax-wholelines-max indeed can potentially cause problems too, but in 
a much narrow range of situations (and only with major modes which have 
non-trivial syntax-propertize-function).

In any case, I would be happy to investigate further improvements in 
Lisp which would be implemented in the same area of code that 
syntax-wholelines-max lives in.

>> I'd really like it if we could scope this discussion to solving that 
>> particular problem. Not the speed of operations in large files in 
>> general.
>>
> 
> I don't understand what you mean.  Which "particular problem"?  The 
> point of this discussion is of course the speed of operations in large 
> files in general.

The particular problem is long lines. It not the same as "large files in 
general".

> If you take that out of the picture, everything is of 
> course possible. I'm not even sure what remains in fact, Emacs is an 
> editor, not a displayer.

The well-known problem we have had for a while is that Emacs screeches 
to a halt even on medium-sized buffers as soon as it encounters a long line.




This bug report was last modified 2 years and 8 days ago.

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