From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=) Newsgroups: gmane.lisp.guile.bugs Subject: bug#12095: Protecting pointer on bytevector with guardian does not protect memory Date: Mon, 08 Oct 2012 15:44:49 +0200 Message-ID: <874nm584dq.fsf@gnu.org> References: <20502.44997.295661.951990@vagabond.local> <878vdskmde.fsf@Kagami.home> <874nm75le8.fsf@gnu.org> <87y5ji2f1y.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1349703949 28052 80.91.229.3 (8 Oct 2012 13:45:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 8 Oct 2012 13:45:49 +0000 (UTC) Cc: 12095@debbugs.gnu.org, Ian Price To: Daniel Hartwig Original-X-From: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Mon Oct 08 15:45:55 2012 Return-path: Envelope-to: guile-bugs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TLDeb-0006ms-OX for guile-bugs@m.gmane.org; Mon, 08 Oct 2012 15:45:54 +0200 Original-Received: from localhost ([::1]:48075 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLDeV-0006bC-Fw for guile-bugs@m.gmane.org; Mon, 08 Oct 2012 09:45:47 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:42391) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLDeN-0006b5-V1 for bug-guile@gnu.org; Mon, 08 Oct 2012 09:45:45 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLDeI-0001hj-PT for bug-guile@gnu.org; Mon, 08 Oct 2012 09:45:39 -0400 Original-Received: from debbugs.gnu.org ([140.186.70.43]:50940) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLDeI-0001hP-Ly for bug-guile@gnu.org; Mon, 08 Oct 2012 09:45:34 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.72) (envelope-from ) id 1TLDej-0007yE-VN for bug-guile@gnu.org; Mon, 08 Oct 2012 09:46:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=) Original-Sender: debbugs-submit-bounces@debbugs.gnu.org Resent-CC: bug-guile@gnu.org Resent-Date: Mon, 08 Oct 2012 13:46:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 12095 X-GNU-PR-Package: guile X-GNU-PR-Keywords: Original-Received: via spool by 12095-submit@debbugs.gnu.org id=B12095.134970392429557 (code B ref 12095); Mon, 08 Oct 2012 13:46:01 +0000 Original-Received: (at 12095) by debbugs.gnu.org; 8 Oct 2012 13:45:24 +0000 Original-Received: from localhost ([127.0.0.1]:32957 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.72) (envelope-from ) id 1TLDe7-0007fw-IO for submit@debbugs.gnu.org; Mon, 08 Oct 2012 09:45:24 -0400 Original-Received: from xanadu.aquilenet.fr ([88.191.123.111]:53835) by debbugs.gnu.org with esmtp (Exim 4.72) (envelope-from ) id 1TLDe3-0007Xk-Br for 12095@debbugs.gnu.org; Mon, 08 Oct 2012 09:45:21 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by xanadu.aquilenet.fr (Postfix) with ESMTP id 3C4F91271; Mon, 8 Oct 2012 15:44:50 +0200 (CEST) Original-Received: from xanadu.aquilenet.fr ([127.0.0.1]) by localhost (xanadu.aquilenet.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IxVuXttC2I8Z; Mon, 8 Oct 2012 15:44:50 +0200 (CEST) Original-Received: from pluto (unknown [193.50.110.215]) by xanadu.aquilenet.fr (Postfix) with ESMTPSA id D4504121A; Mon, 8 Oct 2012 15:44:49 +0200 (CEST) X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 17 =?UTF-8?Q?Vend=C3=A9miaire?= an 221 de la =?UTF-8?Q?R=C3=A9volution?= X-PGP-Key-ID: 0xEA52ECF4 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 83C4 F8E5 10A3 3B4C 5BEA D15D 77DD 95E2 EA52 ECF4 X-OS: x86_64-unknown-linux-gnu In-Reply-To: (Daniel Hartwig's message of "Mon, 8 Oct 2012 07:49:18 +0800") User-Agent: Gnus/5.130005 (Ma Gnus v0.5) Emacs/24.2 (gnu/linux) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.13 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 140.186.70.43 X-BeenThere: bug-guile@gnu.org List-Id: "Bug reports for GUILE, GNU's Ubiquitous Extension Language" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Original-Sender: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.bugs:6547 Archived-At: Hi, Daniel Hartwig skribis: > On 8 October 2012 04:38, Ludovic Court=C3=A8s wrote: >>>> This is expected to fail: =E2=80=98bytevector->pointer=E2=80=99 create= s a weak reference >>>> from the returned pointer object to the given bytevector. So when the >>>> pointer object is reclaimed, the bytevector can be reclaimed too, hence >>>> the problem you=E2=80=99re observing. (And no, guardians don=E2=80=99= t protect objects >>>> from garbage collection.) >>> >>> If I understand correctly, there is never any non-weak reference to >>> the bv above and so it can be collected at any time. >> >> There=E2=80=99s a weak reference from the pointer object to the bytevect= or. >> >> Once that pointer object has been collected (as in the example above), >> the bytevector can be collected anytime. > > Right. But then the pointer is being collected even though it remains > inside the guardian, in the example it is never extracted from there. Well, when the object reaches the guardian=E2=80=99s zombie list, that=E2= =80=99s because it=E2=80=99s been finalized, so any weak references from that object can al= so be nullified. Anyway, guardians are not a mechanism to protect objects from being GC=E2=80=99d. To prevent the bytevector from being GC=E2=80=99d, you shoul= d either keep the pointer object or the bytevector itself in non-GC=E2=80=99d memory, suc= h as a global variable or hash table. How does it help? Should we close the bug? :-) Thanks, Ludo=E2=80=99.