From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Ryan B <public@ryanb.org> Newsgroups: gmane.emacs.devel Subject: Re: Making font-lock handle long lines better Date: Sun, 13 May 2018 12:44:09 -0700 Message-ID: <CA+caGh8DpwKKn3xMQFE+pqbHOVjWPf=Oc1ZJ5x==wCzEts28Aw@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> <CABr8ebY_0sUTmv_unYQSdZ4VjrCf3KNH3nnE2SW_sd-xEdU9+A@mail.gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="0000000000007ed3e0056c1b98df" X-Trace: blaine.gmane.org 1526252011 16854 195.159.176.226 (13 May 2018 22:53:31 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 13 May 2018 22:53:31 +0000 (UTC) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon May 14 00:53:27 2018 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 1fHzrp-0004Hk-Ux for ged-emacs-devel@m.gmane.org; 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charset="UTF-8" for the record, i narrowed this down to the maven element of `compilation-error-regexp-alist'. if i remove that element, `compilation-mode' is fast on the minimal test case in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25682 . it's evidently a somewhat known issue: https://blog.danielgempesaw.com/post/129841682030/fixing-a-laggy-compilation-buffer https://www.reddit.com/r/emacs/comments/2b2j5m/emacs_unresponsive_during_compilebuild/ http://comments.gmane.org/gmane.emacs.bugs/28783 (currently down) On Sat, Feb 11, 2017 at 3:09 PM Anders Lindgren <andlind@gmail.com> wrote: > 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. > > -- https://snarfed.org/ --0000000000007ed3e0056c1b98df Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div>for the record, i narrowed this down to the maven ele= ment of `compilation-error-regexp-alist'. if i remove that element, `co= mpilation-mode' is fast on the minimal test case in <a href=3D"https://= debbugs.gnu.org/cgi/bugreport.cgi?bug=3D25682">https://debbugs.gnu.org/cgi/= bugreport.cgi?bug=3D25682</a> .<br><br></div>it's evidently a somewhat = known issue:<br><a href=3D"https://blog.danielgempesaw.com/post/12984168203= 0/fixing-a-laggy-compilation-buffer">https://blog.danielgempesaw.com/post/1= 29841682030/fixing-a-laggy-compilation-buffer</a><br><a href=3D"https://www= .reddit.com/r/emacs/comments/2b2j5m/emacs_unresponsive_during_compilebuild/= ">https://www.reddit.com/r/emacs/comments/2b2j5m/emacs_unresponsive_during_= compilebuild/</a><br><a href=3D"http://comments.gmane.org/gmane.emacs.bugs/= 28783">http://comments.gmane.org/gmane.emacs.bugs/28783</a>=C2=A0 (currentl= y down)<br> <br></div><br><div class=3D"gmail_quote"><div dir=3D"ltr">On Sa= t, Feb 11, 2017 at 3:09 PM Anders Lindgren <<a href=3D"mailto:andlind@gm= ail.com">andlind@gmail.com</a>> wrote:<br></div><blockquote class=3D"gma= il_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-lef= t:1ex"><div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quot= e"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord= er-left:1px solid rgb(204,204,204);padding-left:1ex">Since it's slow in= Fundamental 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" target=3D"_blank">https://github.com/Lindydancer/highlight-refont= ification</a> to get visual feedback on the font-lock refontification proce= ss.</div><div><br></div></div></div></div> </blockquote></div><br clear=3D"all"><br>-- <br><div dir=3D"ltr" class=3D"g= mail_signature" data-smartmail=3D"gmail_signature"><a href=3D"https://snarf= ed.org/" target=3D"_blank">https://snarfed.org/</a></div> --0000000000007ed3e0056c1b98df--