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: Concurrency via isolated process/thread Date: Fri, 07 Jul 2023 16:34:18 +0300 Message-ID: <83cz13g811.fsf@gnu.org> References: <871qhnr4ty.fsf@localhost> <83v8ezk3cj.fsf@gnu.org> <87v8ezpov0.fsf@localhost> <83r0pnk2az.fsf@gnu.org> <87pm57pns8.fsf@localhost> <87lefvp55t.fsf@yahoo.com> <87sfa28ura.fsf@localhost> <87cz16o8vz.fsf@yahoo.com> <87jzve8r4m.fsf@localhost> <871qhmo5nv.fsf@yahoo.com> <87bkgq8p5t.fsf@localhost> <831qhmjwk0.fsf@gnu.org> <875y6y8nlr.fsf@localhost> <87h6qhnalc.fsf@yahoo.com> <87ilax71wo.fsf@localhost> <831qhli14t.fsf@gnu.org> <87wmzdxewc.fsf@localhost> <83r0plgjeo.fsf@gnu.org> <87o7kpxapo.fsf@localhost> <83mt09gcaf.fsf@gnu.org> <87wmzbc3af.fsf@localhost> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="21200"; mail-complaints-to="usenet@ciao.gmane.io" Cc: luangruo@yahoo.com, emacs-devel@gnu.org To: Ihor Radchenko Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Jul 07 15:34:45 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 1qHlbh-0005KJ-OZ for ged-emacs-devel@m.gmane-mx.org; Fri, 07 Jul 2023 15:34:45 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qHlbH-00069s-99; Fri, 07 Jul 2023 09:34:19 -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 1qHlbF-00069j-Jk for emacs-devel@gnu.org; Fri, 07 Jul 2023 09:34:17 -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 1qHlbE-0003an-RC; Fri, 07 Jul 2023 09:34:16 -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=/gL2+AyxEki2upzOXoZoE5eoG/ebviKOaJ7OKGJaGZ0=; b=sUDZMA7HOJe/ qZVCWhOwWRucL2x8ABq+mSDd5OhI6xAbjluKntAZAyKHykLn/MGAkMViPfaTviCl4ErvF6bMq1mxh KFiC9BbmnUcDTHTa64hcM50+QDrw51I+MdAxDCAfpl1Lw1RV2wQrYURD0CdvldwYIBj2mN+f1MpVT Ok1IfVM+Y0++HqYkbQQT0Gru037L5njkPPF8oG9mjLhe4CisEg1UP/tqUnu72D8wlYsCp304QX9Zo JGIlDxSp52DGFUIh1qmROP3nQSPE6wof8JoaEVDrASibUq4tKhIm+kgGPQHSpPq5f1up9vrFVZyuB 7CZk+wSSjM4iI2tNzyJc6g==; Original-Received: from [87.69.77.57] (helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qHlbE-00084i-AH; Fri, 07 Jul 2023 09:34:16 -0400 In-Reply-To: <87wmzbc3af.fsf@localhost> (message from Ihor Radchenko on Fri, 07 Jul 2023 12:30:16 +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:307571 Archived-At: > From: Ihor Radchenko > Cc: luangruo@yahoo.com, emacs-devel@gnu.org > Date: Fri, 07 Jul 2023 12:30:16 +0000 > > Eli Zaretskii writes: > > >> But 5% CPU time spend allocating memory is not insignificant. > > > > Once again, it isn't necessarily memory allocation per se. For > > example, it could be find_suspicious_object_in_range, called from > > allocate_vectorlike. > > I did not have ENABLE_CHECKING in this benchmark. > It is just ./configure --with-native-compilation > So, find_suspicious_object_in_range should not run at all. Then maybe you should invest some serious time looking into this and figuring out why this happens. Although in my book 5% of run time or even 10% of run time is not the first place where I'd look for optimizations. > maybe need to have multiple heaps. All modern implementation of malloc already do use several different heaps internally. > >> If a thread is working with a temporary buffer and locks it, that > >> buffer has almost 0 chance to be accessed by another thread. > > > > But "working on a buffer" requires access and modification of many > > global structures. Just walk the code in set-buffer and its > > subroutines, and you will see that. > > I was only able to identify the following: > > interrupt_input_blocked > current_buffer > last_known_column_point There are much more: buffer-alist buffer's base-buffer buffer's undo-list buffer's point and begv/zv markers buffer's marker list buffer's local variables (Where the above says "buffer's", it means the buffer that was current before set-buffer.) > AFAIU, current_buffer might be made thread-local and > last_known_column_point can be made buffer-local. The current buffer is already thread-local. > interrupt_input_blocked is more tricky. But it is just one global state > variable. Surely we can find a solution to make it work with multiple threads. Yes, but we have just looked at a single primitive: set-buffer. Once in the buffer, any useful Lisp program will do gobs of stuff, and each one of those accesses more and more globals. How do you protect all that in a 100% reliable way? by identifying the variables and structures one by one? what if tomorrow some change in Emacs adds one more? > >> Same with variables - even if some global variable needs to be locked, > >> it is unlikely that it will need to be accessed by another thread. > > > > I think you misunderstand the frequency of such collisions. > > case-fold-search comes to mind. > > How so? What is the problem with a buffer-local variable that is rarely > set directly (other than by major modes)? let-binding is common, but it > is not a problem. Searching for "setq case-fold-search" finds more than 30 hits in Emacs alone. And this variable is just an example. Like I said: your mental model of the Emacs global state is too optimistic.