Subject: bug#21077: 24.5; Slow printing in inferior python buffer with python-shell-enable-font-lock

From: Ista Zahn <[email-masked]>
Date: Wed, 29 Jul 2015 16:50:03 -0400

On Fri, Jul 17, 2015 at 4:33 AM, Stefan Monnier
<[email-masked]> wrote:
>> It wasn't.  Something is clearly wrong with the regexps involved in
>> this recipe, at least.
>
> The trigger is simple and a well-known problem in Emacs: the command you
> pass to Python outputs one very long line, and Emacs assumes at various places
> that lines aren't too long.  One such assumption is in font-lock itself,
> another appears to be in one of the regexps used in the font-lock config
> of inferior python mode.

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.

Best,
Ista

>         Stefan