From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" Newsgroups: gmane.emacs.bugs Subject: bug#56682: Fix the long lines font locking related slowdowns Date: Mon, 01 Aug 2022 03:11:43 -0400 Message-ID: References: <837d46mjen.fsf@gnu.org> <8a3eaeef01be5bfaa5ef@heytings.org> <05388e8d8812bfa3695d@heytings.org> <83v8rf5894.fsf@gnu.org> <65cb7c73fd4a999cca00@heytings.org> <8c7321f2f3400a5db9be@heytings.org> <8c7321f2f388e5343475@heytings.org> <8c7321f2f36494299e61@heytings.org> <8c7321f2f336523624e3@heytings.org> Reply-To: Stefan Monnier Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="10339"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: 56682@debbugs.gnu.org, Eli Zaretskii To: Gregory Heytings Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Aug 01 09:16:23 2022 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oIPf5-0002an-2P for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 01 Aug 2022 09:16:23 +0200 Original-Received: from localhost ([::1]:39584 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oIPf3-00058v-Rb for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 01 Aug 2022 03:16:21 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:44960) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oIPas-0002dX-6d for bug-gnu-emacs@gnu.org; Mon, 01 Aug 2022 03:12:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:49383) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1oIPar-0006LO-Rb for bug-gnu-emacs@gnu.org; Mon, 01 Aug 2022 03:12:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1oIPar-00068o-Jg for bug-gnu-emacs@gnu.org; Mon, 01 Aug 2022 03:12:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 01 Aug 2022 07:12:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 56682 X-GNU-PR-Package: emacs Original-Received: via spool by 56682-submit@debbugs.gnu.org id=B56682.165933791623595 (code B ref 56682); Mon, 01 Aug 2022 07:12:01 +0000 Original-Received: (at 56682) by debbugs.gnu.org; 1 Aug 2022 07:11:56 +0000 Original-Received: from localhost ([127.0.0.1]:39132 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1oIPal-00068U-U0 for submit@debbugs.gnu.org; Mon, 01 Aug 2022 03:11:56 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:54777) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1oIPak-00068H-CB for 56682@debbugs.gnu.org; Mon, 01 Aug 2022 03:11:54 -0400 Original-Received: from pmg3.iro.umontreal.ca (localhost [127.0.0.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 958A14409BE; Mon, 1 Aug 2022 03:11:48 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 4A9BF4408DC; Mon, 1 Aug 2022 03:11:47 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1659337907; bh=z51RA9DSGPdp0MYRrCHHYEGSPAeriRtk+Wvb/5wZmWk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=OcpmIbvRlahvmjl8+9tDB0wFNw/KyZ5luGygf/VlpKLAGEWhasKHpXaexXWxD+bLR Q8hI0gCCFGEzubrGueM2PXAnxZVn608XLJSDZJsIxlpdOjXgDATM1JVcTbXQDo4Xu6 MO2AtyDtAb82TCR1vve1QIO+X+XePyvLxZL+8lW1pHF2iRss3eep4ayA6fHD6t+8rP g1rNrPe2GkGql1lqAqZHQhbiwPbi+8NGgQHl1Js60B6aKVgbsmNoIhrkoaXGR2ygDe 8sxFC/5G5QV0xhDhkzki9xqTAUZzREUY2vDpXNjJctM86OulGsbcohRkvXmiGH9vRo VJNECZFrYkN8Q== Original-Received: from milanesa (dyn.144-85-174-155.dsl.vtx.ch [144.85.174.155]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 69BCC120315; Mon, 1 Aug 2022 03:11:46 -0400 (EDT) In-Reply-To: <8c7321f2f336523624e3@heytings.org> (Gregory Heytings's message of "Sun, 31 Jul 2022 23:12:32 +0000") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:238389 Archived-At: >> Your current code makes it impossible for a major mode to make Emacs slow >> by widening in a too-long-line. > Which is a good thing, isn't it? No: we don't want to prevent people from shooting themselves in the foot. Basically if it says "impossible" there's a good chance it's not a good thing. > Or do you think that it's okay for Emacs to become unresponsive just > because it is busy highlighting characters in the buffer? Widening in a too long line will not necessarily lead to an unresponsive Emacs, so by preventing it you're also preventing useful cases. >> I'd prefer if we made it easy (i.e. the default) for Emacs to work well in >> that case, without making it impossible for the major mode to mess >> things up. > Sure, I would also welcome a better solution. Until it materializes, the > only reasonable way is to use a less optimal solution. It's not difficult to make it possible to re-widen after your narrowing. > I just sent one such example to Dmitry. And I pointed to another possible > solution, namely to scan the whole buffer while opening it (instead of > scanning it lazily, which is IIUC what currently happens). From a user > viewpoint, it's understandable that opening a big file takes some time. We used to scan eagerly in the background with `jit-lock-stealth`, but that was not very popular (eats up your battery for fairly little benefit). We also have "lazier" highlighting via `jit-lock-defer`, but that hasn't been adapted to `syntax-ppss`. It might be with investigating. Stefan