Received: (at submit) by debbugs.gnu.org; 26 Sep 2020 11:17:38 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Sat Sep 26 07:17:38 2020 Received: from localhost ([127.0.0.1]:45961 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1kM8Cv-0006ww-S8 for submit <at> debbugs.gnu.org; Sat, 26 Sep 2020 07:17:38 -0400 Received: from lists.gnu.org ([209.51.188.17]:42348) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <theo@HIDDEN>) id 1kM8Cr-0006wm-86 for submit <at> debbugs.gnu.org; Sat, 26 Sep 2020 07:17:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58786) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <theo@HIDDEN>) id 1kM8Cq-0005X5-Uh for bug-gnu-emacs@HIDDEN; Sat, 26 Sep 2020 07:17:33 -0400 Received: from out1.migadu.com ([2001:41d0:2:863f::]:37760) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <theo@HIDDEN>) id 1kM8Cm-0004qZ-Pr for bug-gnu-emacs@HIDDEN; Sat, 26 Sep 2020 07:17:32 -0400 X-Report-Abuse: Please report any abuse attempt to abuse@HIDDEN and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=thornhill.no; s=key1; t=1601119045; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type; bh=FR5GZPaZ8C4dz/HWAdha/gZmqev8RZP+oavGs9toxcE=; b=dAWpOOUU1qPE/kDU/sKZKIXEHQ/WLxnpiAy9FWLdqHDAmpddlRr5GSnMAdncFLTFW9yxY4 9kf5P7s7mxa7M3iBXwlwDVo9IVMX0m8xQgiVqi+kY+O97bmIt1UPBlXChioen7UNLG68Dg tR1QAcZki2uzc2qjpQyCbPXGnYgmVgmEpzcbdsf+foAraF2d7adMbUH++2QIAs/gB8GdsQ uhXH+Kib5Rlf9cnaPoyMMywkdsi8DESn3RCCQE8UX+mB9Si8M1ikKaJwAjaPog28lgyLIZ zEaKHsSzxfMczKvofzf/jlpzdXm6+Lo8I5hWuieR5TqG1Jvm3i+g5BAC49fzpA== From: Theodor Thornhill <theo@HIDDEN> To: bug-gnu-emacs@HIDDEN Subject: 28.0.50; CC Mode multiline strings grinds performance to a halt Date: Sat, 26 Sep 2020 13:17:29 +0200 Message-ID: <87lfgwwzw6.fsf@HIDDEN> MIME-Version: 1.0 Content-Type: text/plain X-Spam-Score: -0.10 Received-SPF: pass client-ip=2001:41d0:2:863f::; envelope-from=theo@HIDDEN; helo=out1.migadu.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/26 07:17:26 X-ACL-Warn: Detected OS = ??? X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Spam-Score: -1.4 (-) X-Debbugs-Envelope-To: submit X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -2.4 (--) Hello there! While creating a new mode derived from CC Mode, we noticed performance is affected heavily when setting a character for 'c-multiline-string-start-char'. There is a discussion around this that can be found at https://github.com/josteink/csharp-mode/issues/164, and we were given an easily reproducible repo for this. It is verified to slow typing down both in 'csharp-mode', 'pike-mode' and in this test case: https://github.com/unhammer/csharp-mode/tree/164-repro I think (unconvincingly) that some of the problematic code is situated around line 2047 in 'cc-mode.el', but this is only a guess taken from some light profiling. The issue is described well on github, and I think me trying to reiterate that here will only cause subtle confusions. One thing of note is that you don't even have to have any multiline strings for this performance hit to occur, meaning all 'csharp-mode' files do suffer from this. Let me know if something is still unclear, and I'll try to bring up some more information. All the best, Theodor Thornhill
Theodor Thornhill <theo@HIDDEN>
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