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: MPS: weak hash tables Date: Sun, 07 Jul 2024 20:49:51 +0300 Message-ID: <86jzhx148w.fsf@gnu.org> References: <878qyeffjh.fsf@localhost> <8734olzlws.fsf@gmail.com> <867cdx32e3.fsf@gnu.org> <864j912t0s.fsf@gnu.org> <86zfqt1cxa.fsf@gnu.org> <86y16d1aik.fsf@gnu.org> <86tth119bs.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="34074"; mail-complaints-to="usenet@ciao.gmane.io" Cc: pipcet@protonmail.com, eller.helmut@gmail.com, yantar92@posteo.net, emacs-devel@gnu.org To: Gerd =?utf-8?Q?M=C3=B6llmann?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Jul 07 19:50:25 2024 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 1sQW1o-0008fA-Vq for ged-emacs-devel@m.gmane-mx.org; Sun, 07 Jul 2024 19:50:25 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sQW1M-0005bU-Pg; Sun, 07 Jul 2024 13:49:56 -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 1sQW1K-0005b3-Bm for emacs-devel@gnu.org; Sun, 07 Jul 2024 13:49:54 -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 1sQW1J-0002ka-QR; Sun, 07 Jul 2024 13:49:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=MIME-version:References:Subject:In-Reply-To:To:From: Date; bh=glvl8/qQjOicF4B8OLdiQIGrqO+GLbBJDAWBOHlfcIY=; b=Ixl2/5lAkZiDzjPMfMSi JgyHJNm9IqKUgzYeehRym2rPZZfRwDf69bT+KN0D9vC4v9vCScmCmVfZcyEvEQjqW/RqphCIGFXQx uNOISkK1CqT9A/uhPTXQTiBqGKSwR8vBAXzUiHMcbyZDgMi7MdLUr4pVFbZsvb5OOvB1ltu4WYopG sHPtaRXrDy5f1QH1Y5cpHpvLqsstoIxTcHytIKdxe0M18v+fDNE7RircdDbWeaJCGGyDuZYvc0lsZ Lb1iNw3qCbT37CmqAQVh5A0mn9yuWu2nbyBOrn2QVhFSUJol74NcRe0B4rmnViOMstIUqngZBlWH1 zWIEyK0URoEQJw==; In-Reply-To: (message from Gerd =?utf-8?Q?M=C3=B6llmann?= on Sun, 07 Jul 2024 19:08:45 +0200) 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:321511 Archived-At: > From: Gerd Möllmann > Cc: pipcet@protonmail.com, eller.helmut@gmail.com, yantar92@posteo.net, > emacs-devel@gnu.org > Date: Sun, 07 Jul 2024 19:08:45 +0200 > > Eli Zaretskii writes: > > > But does igc know that an interval is no longer needed? How does it > > know that when sweep_intervals in the old GC needed to do that > > explicitly in C? > > It's kind of mark-sweep vs. copying collector algorithms. > > The mark phase of mark-sweep marks all objects reachable from roots, > then the sweep phase frees what's not marked. > > A copying collector copies every object reachable from roots. At the > end, what has not been copied is implicitly unreachable. > > MPS is a copying collection, with some additional complications, like > ambiguous references (-> mostly-copying), and incrementality (-> > barriers), but the principle is still the same. I understand all that, but unchaining an interval involves the need to modify the pointers of its adjacent nodes, and how can MPS do that without understanding our data structures?