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: Wed, 05 Jul 2023 16:51:43 +0300 Message-ID: <831qhmjwk0.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> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="32289"; 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 Wed Jul 05 15:52:43 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 1qH2vy-0008Ab-MP for ged-emacs-devel@m.gmane-mx.org; Wed, 05 Jul 2023 15:52:42 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qH2v6-00042c-R9; Wed, 05 Jul 2023 09:51:48 -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 1qH2v5-000421-CI for emacs-devel@gnu.org; Wed, 05 Jul 2023 09:51:47 -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 1qH2v4-0006RK-RE; Wed, 05 Jul 2023 09:51:46 -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=IN4+BUltW/25LjU2o2JM1TC9OQR6kn3ixrDKiN4FRQU=; b=GCSzjQo+CUFx 2ns5o2kQKUhewFPfAcgNp+I3euTDo3ut0xmyZVQsEEAE3Bub1ofgtFHBFc6GJ0v3LfrX7yeO8oXfA EnhPC+2xIejMKc7lb81s5IWtYZJHocZVzTsj2DtzcHaMF/g38utbOAY6dKPvw5pe1o2GOB5AbfzUU f/T+Ywiwrim8csN7wvEnfzmLYD6sKn/KEmqIqQbS2vwNVHh1IdyuilU5xGWtX35wWdmfoWFHzmlyj wTpE2Qh9/gOhP6ZiU2sZI1RAOdp2x1LM9v7vwdKHFwrH2ke7SnCk//UxTwJDZEzIXTG/iBrBIc8cm x6AhrVAeP+RApnP2ytIn4w==; 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 1qH2v4-00013k-Bn; Wed, 05 Jul 2023 09:51:46 -0400 In-Reply-To: <87bkgq8p5t.fsf@localhost> (message from Ihor Radchenko on Wed, 05 Jul 2023 13:26:54 +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:307473 Archived-At: > From: Ihor Radchenko > Cc: Eli Zaretskii , emacs-devel@gnu.org > Date: Wed, 05 Jul 2023 13:26:54 +0000 > > > If Emacs is to take any more advantage of SMP systems, it > > must be properly interlocked, with multiple processors sharing the same > > memory. This lesson was learned decades ago with another program: > > vmunix. > > AFAIU, one of the big blockers of this is single-threaded GC. Emacs > cannot free/allocate memory asynchronously. Or do I miss something? Why is that a "big blocker"? GC runs "whenever it is convenient" anyway, so it can be delayed until that time, and run from the main thread, perhaps sacrificing the memory footprint a bit. The real "big blocker" is that a typical Emacs session has a huge global state, which cannot be safely modified by more than a single thread at a time, and even if one thread writes while the other reads is in many cases problematic.