From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Emacs design and architecture. How about copy-on-write? Date: Fri, 22 Sep 2023 19:14:53 +0300 Message-ID: <83il825gn6.fsf@gnu.org> References: <87sf7fc7kd.fsf@dataswamp.org> <834jjuk68t.fsf@gnu.org> <87cyyhc7uu.fsf@dataswamp.org> <83ttrsg9nx.fsf@gnu.org> <83h6nrg4eg.fsf@gnu.org> <83v8c7elan.fsf@gnu.org> <877conk5ny.fsf@localhost> <83ttrreeu0.fsf@gnu.org> <87bkdzeas1.fsf@localhost> <83cyyfe5l8.fsf@gnu.org> <8734zbyu6o.fsf@dataswamp.org> <835y46e8o9.fsf@gnu.org> <87zg1ixvnc.fsf@dataswamp.org> <83sf7acp86.fsf@gnu.org> <87led2x8ao.fsf@dataswamp.org> <83r0mtaupr.fsf@gnu.org> <87pm2ae19p.fsf@dataswamp.org> <83lecy5hps.fsf@gnu.org> <87bkdu6vd1.fsf@localhost> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="27588"; mail-complaints-to="usenet@ciao.gmane.io" Cc: incal@dataswamp.org, emacs-devel@gnu.org To: Ihor Radchenko Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Sep 22 18:15:18 2023 Return-path: Envelope-to: ged-emacs-devel@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 1qjioI-0006xv-9e for ged-emacs-devel@m.gmane-mx.org; Fri, 22 Sep 2023 18:15:18 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qjinn-0003HK-NH; Fri, 22 Sep 2023 12:14:47 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qjinl-0003GN-U9 for emacs-devel@gnu.org; Fri, 22 Sep 2023 12:14:45 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qjink-0001Av-Qg; Fri, 22 Sep 2023 12:14:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=DnKcrT2wJoF8ySsd5ICcbBPvS/SPFrMtXp9fHtHaD28=; b=auKcIDLfSb3f ouj+cQIMhagJpxBRgidAKD5Yjys2z0JMRlMO5tpG3nlHW2K/S/zM36MW2JK+kRFYPNf9x5tx8DPgB ca2X7roRByx7oKh8MqdkxuuOeozS3+FB/PRF3Q4RuNukZWJXzP9EVEi6oI/JH3cU/yI6nKCBgbOcN RM8XG0Dn3qEBWuy+R88oM39A9+zW+qS+wT3UVbtZGnGQIA3uq3nILTOGT6ay5H8kWEtj/9GxQiBDG /5bHCNwpnVwMdpkNS15wW5WuQFdwE4n3P5QT7owsopxOVXyVeYh7NR46as4dkU60SGgUW+Rf9Mnfe SUnJOb4X9U9HPpqTzSdwBQ==; In-Reply-To: <87bkdu6vd1.fsf@localhost> (message from Ihor Radchenko on Fri, 22 Sep 2023 16:11:38 +0000) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:310980 Archived-At: > From: Ihor Radchenko > Cc: Emanuel Berg , emacs-devel@gnu.org > Date: Fri, 22 Sep 2023 16:11:38 +0000 > > Eli Zaretskii writes: > > > So one thread uses setq, releases the lock, then another thread comes, > > takes the lock and changes the value of that variable, and when the > > first thread uses the variable after that, it will have a value > > different from the one the thread used in its setq? How can one write > > a program under these conditions and know what it will do? > > IMHO, there should be a new API to lock global variables by async > threads and/or set them. Which again means existing Lisp programs will be unable to run without very serious changes. > 1. Thread does not rely upon global variable value being constant, only > upon being able to set it. This is an almost empty set in Emacs. > 2. Thread sets global variable value and uses it later, expecting the > value to remain constant. This is the problem to solve. > 3. Thread let-binds global variable. This is already solved in the current Lisp threadfs.