From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.bugs Subject: bug#52298: 29.0.50; Frequent redisplay cycles induced by c-type-finder-timer-func timer in CC Mode Date: Mon, 6 Dec 2021 20:53:15 +0000 Message-ID: References: <83sfv74hpm.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="21761"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 52298@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Dec 06 21:54:19 2021 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 1muL07-0005Ho-BQ for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 06 Dec 2021 21:54:19 +0100 Original-Received: from localhost ([::1]:51662 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1muL06-0006yD-3d for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 06 Dec 2021 15:54:18 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:42550) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1muKzq-0006y1-Ex for bug-gnu-emacs@gnu.org; Mon, 06 Dec 2021 15:54:02 -0500 Original-Received: from debbugs.gnu.org ([209.51.188.43]:52215) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1muKzq-0003UJ-7J for bug-gnu-emacs@gnu.org; Mon, 06 Dec 2021 15:54:02 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1muKzq-0000NC-1k for bug-gnu-emacs@gnu.org; Mon, 06 Dec 2021 15:54:02 -0500 X-Loop: help-debbugs@gnu.org Resent-From: Alan Mackenzie Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 06 Dec 2021 20:54:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 52298 X-GNU-PR-Package: emacs X-Debbugs-Original-Cc: bug-gnu-emacs@gnu.org Original-Received: via spool by submit@debbugs.gnu.org id=B.16388240051387 (code B ref -1); Mon, 06 Dec 2021 20:54:01 +0000 Original-Received: (at submit) by debbugs.gnu.org; 6 Dec 2021 20:53:25 +0000 Original-Received: from localhost ([127.0.0.1]:35528 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1muKzE-0000MI-OR for submit@debbugs.gnu.org; Mon, 06 Dec 2021 15:53:25 -0500 Original-Received: from lists.gnu.org ([209.51.188.17]:53318) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1muKzB-0000M9-SY for submit@debbugs.gnu.org; Mon, 06 Dec 2021 15:53:23 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:42484) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1muKzB-0006xW-EQ for bug-gnu-emacs@gnu.org; Mon, 06 Dec 2021 15:53:21 -0500 Original-Received: from colin.muc.de ([193.149.48.1]:18763 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1muKz8-0003Qp-Sy for bug-gnu-emacs@gnu.org; Mon, 06 Dec 2021 15:53:21 -0500 Original-Received: (qmail 13305 invoked by uid 3782); 6 Dec 2021 20:53:16 -0000 Original-Received: from acm.muc.de (p4fe15d73.dip0.t-ipconnect.de [79.225.93.115]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Mon, 06 Dec 2021 21:53:16 +0100 Original-Received: (qmail 402 invoked by uid 1000); 6 Dec 2021 20:53:15 -0000 Content-Disposition: inline In-Reply-To: <83sfv74hpm.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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:221787 Archived-At: Hello, Eli. On Sun, Dec 05, 2021 at 09:46:29 +0200, Eli Zaretskii wrote: > It used to be the case that starting "emacs -Q" and disabling > blink-cursor-mode and global-eldoc-mode was enough to get me Emacs > that doesn't perform redisplay unless required. To see this, do the > following with any Emacs up to and including Emacs 28: > emacs -Q > M-x blink-cursor-mode RET > M-x global-eldoc-mode RET > M-x trace-redisplay RET > (The last command is only available if you configured with > "--enable-checking=yes,glyphs".) This would produce a few lines of > output on stderr, and then stop until you do something in Emacs, like > move the cursor with an arrow key. > This is no longer the case in Emacs 29. There, if you visit a C file, > you will see a flurry of stderr messages about constant redisplay > cycles being forced. It seems like the culprit is the function > 'c-type-finder-timer-func', which is run from a timer at 10 Hz (!), That is customisable with c-type-finder-repeat-time. The idea is to have this as often as possible so that the backgroud scanning is complete as soon as possible. (See my next paragraph.) > and which for some reason forces Emacs to perform a redisplay cycle > with that frequency. The trace itself, viz.: > redisplay_internal 0 > 071a03c8 (xdisp.c): try_window_id 2 > redisplay_preserve_echo_area (8) > means that the processing induced by that timer function is far from > being trivial, which means something that this function does causes > Emacs to think some real change might have happened in the buffer. The idea is that this processing only happens a short while after loading a C file, the time being taken up by checking for the fontification of "found types", that is identifiers identified as types in the rest of the buffer somewhere. > Not even "emacs -Q -D" is enough to get rid of this > 'c-type-finder-timer-func' timer in CC Mode buffers. If this processing continues beyond the time to scan all CC Mode buffers, then there is a bug. A megabyte long file (xdisp.c) scans in aroung 18 seconds on my machine. > Is it possible to prevent this frequent timer from firing when no > changes have been done to the buffer? And in any case, please try to > include some logic in that function to avoid whatever it does now to > force such frequent non-trivial redisplay cycles. If nothing else, > laptop users will hate us if we release Emacs with this behavior. It can be disabled by setting (or customising) c-type-finder-time-slot to nil. As I say, the activity should cease after a few seconds, or a few minutes with a well filled desktop. There have been a couple of bugs in this area recently, one fixed (stupidly) on the release branch (where there wasn't a problem). The other one was fixed in master. By recently, I mean last Wednesday and Saturday 2021-11-13. But even given the above, I've a sneaking suspicion there's still a bug here, which I'll have a look for (but not tonight). > In GNU Emacs 29.0.50 (build 297, i686-pc-mingw32) > of 2021-12-04 built on HOME-C4E4A596F7 > Repository revision: f247fa5d5ce7cb34f23c979c17b14c5713eb5490 > Repository branch: master > Windowing system distributor 'Microsoft Corp.', version 5.1.2600 > System Description: Microsoft Windows XP Service Pack 3 (v5.1.0.2600) > Configured using: > 'configure -C --prefix=/d/usr --with-wide-int > --enable-checking=yes,glyphs 'CFLAGS=-O0 -gdwarf-4 -g3'' [ .... ] -- Alan Mackenzie (Nuremberg, Germany).