GNU bug report logs - #21077
24.5; Slow printing in inferior python buffer with python-shell-enable-font-lock

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Package: emacs;

Reported by: Ista Zahn <istazahn <at> gmail.com>

Date: Thu, 16 Jul 2015 17:06:02 UTC

Severity: minor

Tags: fixed

Found in version 24.5

Fixed in version 25.1

Done: npostavs <at> users.sourceforge.net

Bug is archived. No further changes may be made.

Full log

Message #32 received at 21077 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
To: Ista Zahn <istazahn <at> gmail.com>
Cc: 21077 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>
Subject: Re: bug#21077: 24.5; Slow printing in inferior python buffer with
 python-shell-enable-font-lock
Date: Thu, 30 Jul 2015 19:19:50 -0400

> Sorry for the delay in responding. I think a reasonable short term
> measure is to set python-shell-enable-font-lock to nil by default, and
> perhaps add a warning to the doc string to the effect that setting it
> to a non-nil value can dramatically slow down printing.

As mentioned, font-lock is but one of the parts of Emacs that slow down
as lines get longer.

In the case of comint modes, rather than disable font-lock we should
refrain from font-locking the text after the last \n (since that's the
line that keeps getting expanded, so we end up re-font-locking it O(N)
times for a line of length N, for a total amount of work of O(N^2)).
IIRC I have a similar hack in grep.el or compile.el.


        Stefan
This bug report was last modified 8 years and 316 days ago.

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