From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Anders Lindgren <andlind@gmail.com> Newsgroups: gmane.emacs.devel Subject: Re: Making font-lock handle long lines better Date: Sun, 12 Feb 2017 00:06:41 +0100 Message-ID: <CABr8ebY_0sUTmv_unYQSdZ4VjrCf3KNH3nnE2SW_sd-xEdU9+A@mail.gmail.com> References: <CA+caGh_JN9FRi71VjUTwvYBKKygG-KuGGoe3GBgjthPRh00nRg@mail.gmail.com> <83wpcy2eun.fsf@gnu.org> <CAFXAjY4ED1L=T1zB-v=U-_DWbkOaO8+4cDidejBunS-RC3D7zQ@mail.gmail.com> <83lgtc3215.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a114e1ce27876910548494490 X-Trace: blaine.gmane.org 1486854413 11745 195.159.176.226 (11 Feb 2017 23:06:53 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 11 Feb 2017 23:06:53 +0000 (UTC) Cc: Wilfred Hughes <me@wilfred.me.uk>, public@ryanb.org, emacs-devel <emacs-devel@gnu.org> To: Eli Zaretskii <eliz@gnu.org> Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Feb 12 00:06:49 2017 Return-path: <emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org> Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from <emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org>) id 1ccgki-0002dA-GS for ged-emacs-devel@m.gmane.org; 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Sat, 11 Feb 2017 15:06:42 -0800 (PST) Original-Received: by 10.31.52.129 with HTTP; Sat, 11 Feb 2017 15:06:41 -0800 (PST) In-Reply-To: <83lgtc3215.fsf@gnu.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2607:f8b0:400c:c05::232 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." <emacs-devel.gnu.org> List-Unsubscribe: <https://lists.gnu.org/mailman/options/emacs-devel>, <mailto:emacs-devel-request@gnu.org?subject=unsubscribe> List-Archive: <http://lists.gnu.org/archive/html/emacs-devel/> List-Post: <mailto:emacs-devel@gnu.org> List-Help: <mailto:emacs-devel-request@gnu.org?subject=help> List-Subscribe: <https://lists.gnu.org/mailman/listinfo/emacs-devel>, <mailto:emacs-devel-request@gnu.org?subject=subscribe> Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" <emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org> Xref: news.gmane.org gmane.emacs.devel:212250 Archived-At: <http://permalink.gmane.org/gmane.emacs.devel/212250> --001a114e1ce27876910548494490 Content-Type: text/plain; charset=UTF-8 > > Since it's slow in Fundamental mode as well, it's unrelated to > font-lock, and thus to this thread. Display of very long lines is > known to be slow in Emacs. > I believe this is a font-lock problem. If you disable global-font-lock-mode before you open the file, it opens in seconds. If global-font-lock-mode is active Emacs stops responding (I gave up after a few minutes). A quick experiment suggested that the problem is the member `font-lock-extend-region-wholelines' of `font-lock-extend-region-functions' that ensures that whenever font-lock highlights keywords in a region, the full line is rehighlighted (in the case of the example, the full 18M). By removing it, font-locking the file is done in seconds. (I assume that only the visible parts of the buffer is highlighted.) Clearly, simple dropping the function is not a good idea, as keyword fontification could start anywhere on the line, e.g. in the middle of identifiers. A better approach would be to extend the region to include 10KB in either direction, plus ensure that the region isn't split in the middle of identifiers. / Anders Ps. In case anybody is interested in looking further into this, you can use the tool https://github.com/Lindydancer/highlight-refontification to get visual feedback on the font-lock refontification process. --001a114e1ce27876910548494490 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo= ckquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left= :1px solid rgb(204,204,204);padding-left:1ex">Since it's slow in Fundam= ental mode as well, it's unrelated to<br> font-lock, and thus to this thread.=C2=A0 Display of very long lines is<br> known to be slow in Emacs.<br></blockquote><div><br></div><div>I believe th= is is a font-lock problem. If you disable global-font-lock-mode before you = open the file, it opens in seconds. If global-font-lock-mode is active Emac= s stops responding (I gave up after a few minutes).</div><div><br></div><di= v>A quick experiment suggested that the problem is the member `font-lock-ex= tend-region-wholelines' of `font-lock-extend-region-functions' that= ensures that whenever font-lock highlights keywords in a region, the full = line is rehighlighted (in the case of the example, the full 18M). By removi= ng it, font-locking the file is done in seconds. (I assume that only the vi= sible parts of the buffer is highlighted.)</div><div><br></div><div>Clearly= , simple dropping the function is not a good idea, as keyword fontification= could start anywhere on the line, e.g. in the middle of identifiers. A bet= ter approach would be to extend the region to include 10KB in either direct= ion, plus ensure that the region isn't split in the middle of identifie= rs.</div><div><br></div><div>=C2=A0 =C2=A0/ Anders</div><div><br></div><div= >Ps. In case anybody is interested in looking further into this, you can us= e the tool=C2=A0<a href=3D"https://github.com/Lindydancer/highlight-refonti= fication">https://github.com/Lindydancer/highlight-refontification</a> to g= et visual feedback on the font-lock refontification process.</div><div><br>= </div></div></div></div> --001a114e1ce27876910548494490--