bug#19266: 24.4; Font-related window redrawing delays on OS X

[Kirill Ignatiev <kirill.ignatiev@gmail.com>]

I tried looking into this a bit more, and I'm not very familiar with
emacs's internals.

I find that many faces that were previously used get garbage collected
(I see macfont_close being called from cleanup_vector), but I don't
know how faces are stored, nor do I understand why they are no longer
referenced (common sense suggests that they should remain in memory as
long as the buffer that used them is still there). It seems that the
faces are not actively used for displaying the buffer, but can be
expected to be reused in a short time (e.g., region face or comment
face).

Can someone explain where faces are stored and why they are no longer
referenced, even though the buffer that used them is still active?

I am not sure if this is related to this bug, but there is a constant
CLEAR_FACE_CACHE_COUNT (=500) that causes face cache to be cleared
every 500 redisplays. Does anyone understand why this is really
necessary? If the fonts/faces are still in use, that seems wasteful,
unless I misunderstand something.

On 4 December 2014 at 05:19, Sebastian Wiesner <swiesner@lunaryorn.com> wrote:
>
>> Am 04.12.2014 um 11:17 schrieb Eli Zaretskii <eliz@gnu.org>:
>>
>>> From: Sebastian Wiesner <swiesner@lunaryorn.com>
>>> Date: Thu, 4 Dec 2014 10:55:21 +0100
>>> Cc: Kirill Ignatiev <kirill.ignatiev@gmail.com>,
>>> 19266@debbugs.gnu.org
>>>
>>>> Please ask those persons to report here directly, and to read the
>>>> responses and discussions.
>>>
>>> So here I am.
>>
>> Thanks for responding.
>>
>>> How do I subscribe to this bug so that I get replies per mail?
>>
>> You will be CC'ed on responses, so no need to subscribe.
>>
>>>> Optimize your font configuration, so that the font search becomes
>>>> faster.
>>>
>>> I do not know about the OP, but I do not have any “font configuration”.  All that I do is `(set-frame-font "Source Code Pro-13" nil t)'.
>>
>> I meant your system-wide font configuration, not what you do in Emacs.
>
> I don't have that either :)  OS X comes with all sorts of fonts pre-installed, and I just added some five fonts or so.
>
>>> Besides, I'm no font expert at all, so how am I supposed do “optimize” my fonts?
>>
>> Sorry, I don't know that.  If you didn't install too many optional
>> fonts that didn't come with your system, then I think you are already
>> set.  Otherwise, perhaps some OS X expert, here or on some other
>> forum, could help.