From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: ludo@gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) Newsgroups: gmane.lisp.guile.devel Subject: Re: BDW-GC branch updated Date: Tue, 18 Aug 2009 15:18:31 +0200 Message-ID: <871vn95kgo.fsf@gnu.org> References: <87vdkle3qr.fsf@gnu.org> <87r5v9s4av.fsf@delenn.lan> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1250601563 16052 80.91.229.12 (18 Aug 2009 13:19:23 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 18 Aug 2009 13:19:23 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Tue Aug 18 15:19:16 2009 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MdOap-0000ZN-Tk for guile-devel@m.gmane.org; Tue, 18 Aug 2009 15:19:16 +0200 Original-Received: from localhost ([127.0.0.1]:39597 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MdOao-0004RG-T7 for guile-devel@m.gmane.org; Tue, 18 Aug 2009 09:19:14 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MdOaj-0004Pf-C6 for guile-devel@gnu.org; Tue, 18 Aug 2009 09:19:09 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MdOac-0004P0-WF for guile-devel@gnu.org; Tue, 18 Aug 2009 09:19:08 -0400 Original-Received: from [199.232.76.173] (port=55858 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MdOac-0004Ox-R1 for guile-devel@gnu.org; Tue, 18 Aug 2009 09:19:02 -0400 Original-Received: from lo.gmane.org ([80.91.229.12]:39537) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MdOac-0007g9-Ad for guile-devel@gnu.org; Tue, 18 Aug 2009 09:19:02 -0400 Original-Received: from list by lo.gmane.org with local (Exim 4.50) id 1MdOaX-0000SB-87 for guile-devel@gnu.org; Tue, 18 Aug 2009 15:18:57 +0200 Original-Received: from laptop-147-210-128-170.labri.fr ([147.210.128.170]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 18 Aug 2009 15:18:57 +0200 Original-Received: from ludo by laptop-147-210-128-170.labri.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 18 Aug 2009 15:18:57 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 58 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: laptop-147-210-128-170.labri.fr X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 1 Fructidor an 217 de la =?iso-8859-1?Q?R=E9volution?= X-PGP-Key-ID: 0xEA52ECF4 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 821D 815D 902A 7EAB 5CEE D120 7FBA 3D4F EB1F 5364 X-OS: x86_64-unknown-linux-gnu User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) Cancel-Lock: sha1:IREd92xxmuY7NrWehRGmKLG5kpA= X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:9147 Archived-At: Hi, Andreas Rottmann writes: > ludo@gnu.org (Ludovic Courtès) writes: [...] >> So now is a good time to test it and report back! It requires libgc 7.1 >> or later, which isn't packaged in Debian, although it was released in >> May 2008. >> > It's in experimental since recently; I assume its maintainer will upload > to unstable soonish. Good. > Will going from a precise GC to BDW-GC not have drawbacks? IIRC, the PLT > people went in the opposite direction. A quick google turned up this: > > http://www.cs.brown.edu/pipermail/plt-scheme/2006-June/013840.html > > I wonder if the reasons for switching to a precise GC listed in there > will also apply to Guile. Thanks for the link! They write: There is one known problem, though, related to linked lists [Boehm, POPL'02]. Unfortunately, we seem to hit this problem often in practice, due to the way that threads and continuations are implemented, and there doesn't seem to be a reliable way around it. The paper is "Bounding Space Usage of Conservative Garbage Collectors", available from http://www.hpl.hp.com/personal/Hans_Boehm/gc/ . It depicts scenarios where "false references" lead to unbounded data retention. My interpretation of these scenarios and the "Summary" section is that these cases are hopefully quite rare. Now, I don't have enough experience of long-running BDW-GC applications to know whether it's a problem in practice. The PLT folks surely had more experience (but with a different implementation IIUC). There are also other schemes that use BDW-GC, such as Bigloo. However, it doesn't worry me as much as the current GC bugs (e.g., [0, 1]). Also, there are definite benefits to using a conservative GC for libguile, given how tightly it can be integrated with C (e.g., [2]). What do you think? Thanks, Ludo'. [0] http://permalink.gmane.org/gmane.lisp.guile.devel/6832 [1] http://lists.gnu.org/archive/html/guile-devel/2008-08/msg00120.html [2] http://lists.gnu.org/archive/html/guile-devel/2008-11/msg00009.html