From: Lars Ingebrigtsen <larsi@gnus.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 33275@debbugs.gnu.org
Subject: bug#33275: 27.0.50; Image cache pruning
Date: Fri, 09 Nov 2018 13:26:50 +0100 [thread overview]
Message-ID: <m3r2fu5tdh.fsf@gnus.org> (raw)
In-Reply-To: <83bm72ciyz.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 06 Nov 2018 17:40:36 +0200")
Eli Zaretskii <eliz@gnu.org> writes:
> After thinking about this and looking at the code, I don't think I
> understand your proposal(s). Here are the issues that I saw with what
> I think you proposed:
>
> . The hash table used by the image cache is not a Lisp hash-table, so
> weakness doesn't apply. We cache pointers to C structs, so using a
> Lisp hash-tables would need "some work".
Yeah, it'd have to be rewritten substantially to use Lisp hash tables.
> . The code you show above is called from redisplay, so it will not be
> executed as long as a Lisp program (such as the one you show at the
> beginning of this discussion) runs, and you will still have the OOM
> killer get you before that code get a chance to clear the cache.
That's true, but calling the cache pruning function from the function
that enters images into the cache would be trivial, I think.
> . Running such code from GC could be tricky, because freeing images
> needs to remove references of those images from the glyph matrices,
> and that cannot be safely done from arbitrary places.
Ah, I see. Yes, that's a major complication...
> I think if we want to prevent the OOM killer from killing Emacs due to
> many cached images, we should inspect inside cache_image the current
> VM size of the process (like system_process_attributes does), compare
> it to the memory limits, and display a warning and/or signal an error
> when we get dangerously close to the limit.
I think that sounds like a good idea, yes. Having such a check is good
for Emacs sanity, but we should also have a way for programmers to avoid
ending up in that pathological situation to begin with.
So either a DONT-CACHE parameter to `image-size' or just a docstring
thing. :-)
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2018-11-09 12:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-05 14:07 bug#33275: 27.0.50; Image cache pruning Lars Ingebrigtsen
2018-11-05 16:05 ` Eli Zaretskii
2018-11-05 16:18 ` Lars Ingebrigtsen
2018-11-05 16:23 ` Eli Zaretskii
2018-11-05 16:35 ` Lars Ingebrigtsen
2018-11-05 17:27 ` Eli Zaretskii
2018-11-05 17:36 ` Lars Ingebrigtsen
2018-11-05 17:48 ` Lars Ingebrigtsen
2018-11-05 18:14 ` Eli Zaretskii
2018-11-05 18:35 ` Eli Zaretskii
2018-11-05 19:13 ` Lars Ingebrigtsen
2018-11-05 19:28 ` Eli Zaretskii
2018-11-09 12:22 ` Lars Ingebrigtsen
2018-11-06 15:40 ` Eli Zaretskii
2018-11-09 12:26 ` Lars Ingebrigtsen [this message]
2018-11-10 9:48 ` Eli Zaretskii
2019-09-21 8:18 ` Lars Ingebrigtsen
2018-11-05 18:18 ` Eli Zaretskii
2018-11-05 19:06 ` Lars Ingebrigtsen
2018-11-05 19:24 ` Eli Zaretskii
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