From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp0 ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms11 with LMTPS id yBLsH+0qVmAJKgAA0tVLHw (envelope-from ) for ; Sat, 20 Mar 2021 17:03:41 +0000 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp0 with LMTPS id CHe6G+0qVmAoCAAA1q6Kng (envelope-from ) for ; Sat, 20 Mar 2021 17:03:41 +0000 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id DE12D1E642 for ; Sat, 20 Mar 2021 18:03:40 +0100 (CET) Received: from localhost ([::1]:52606 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNf0m-0000CC-0X for larch@yhetil.org; Sat, 20 Mar 2021 13:03:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58598) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNevT-0004oD-7o for guix-devel@gnu.org; Sat, 20 Mar 2021 12:58:11 -0400 Received: from fencepost.gnu.org ([2001:470:142:3::e]:56354) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNevS-0003PW-BW; Sat, 20 Mar 2021 12:58:10 -0400 Received: from [2a01:e0a:1d:7270:af76:b9b:ca24:c465] (port=33496 helo=ribbon) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1lNevQ-0007KT-On; Sat, 20 Mar 2021 12:58:09 -0400 From: =?utf-8?Q?Ludovic_Court=C3=A8s?= To: raid5atemyhomework Subject: Re: A Critique of Shepherd Design References: X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 30 =?utf-8?Q?Vent=C3=B4se?= an 229 de la =?utf-8?Q?R?= =?utf-8?Q?=C3=A9volution?= X-PGP-Key-ID: 0x090B11993D9AEBB5 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 3CE4 6455 8A84 FDC6 9DB4 0CFB 090B 1199 3D9A EBB5 X-OS: x86_64-pc-linux-gnu Date: Sat, 20 Mar 2021 17:58:06 +0100 In-Reply-To: (raid5atemyhomework@protonmail.com's message of "Fri, 19 Mar 2021 17:33:57 +0000") Message-ID: <87a6qx7of5.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "guix-devel@gnu.org" Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: "Guix-devel" X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1616259821; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=Cer8p7Krw2kZ9RlRwbZn4yOoRE9M+AV+vN6er5n+cvU=; b=PxyWSj5MeC5E57/NWttYyiapdAKVIi62YffwhsbCgKtuC+jWN4Zk0Mv6H3QhVd52I6lrmh EtVj5+lL2IQvLUPEjEzCz6H+LhqHjG1Ornx1DjLR8JrQaNdUEq5yRbPlWvdKQVS12yVEWK TfhgtNg8ZoqbQjfWZ8by0fY+PR0+AQ2UvcD0a64d4Bo8hhaKqbJQyBktiOl1qdT8S+DzCO N01o7QNjjlBDB4uJyeCkLostHf5ZKwQgSRUDzelirZMqsDKhcD3g608XO8+1UHw78Af8Xw /CgKq1WFeY6XSC6ohQsVOoEd7Arvoxl69DVu8Cug5wS0w8FKLeosKKbptBGaUA== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1616259821; a=rsa-sha256; cv=none; b=mdB8gyYpq9zaustqerCmDTxlu8cNlrbLIodrugWM9EHfJROjqc4a05faqXoCTj1V5y89vc 66pgRDUbLugxRzu3zIGoQBC0LueAxiLQ2IiRbvKYlhxnpjXwxut0JzQSE6Oxoog1lwNfbb 8uETvLr5oLKmC9IZI1ztcztcoOuzk64EIAdzFl7KKuU2GQ4g9837B8slmCiyIEqfOyD3US RKoEfbfNh7k42M8V4DifReaVpLOwEuAt7WdYf5FabPtSYPMfl4SChA3Z0AkCDzCV3LGBB/ rdyg7GWGHoFNeFC5YlaJtJcWipmaidLohJR4wU8VHxLcANCFicxNjuUGOo61Lg== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=none; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of guix-devel-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=guix-devel-bounces@gnu.org X-Migadu-Spam-Score: -2.91 Authentication-Results: aspmx1.migadu.com; dkim=none; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of guix-devel-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=guix-devel-bounces@gnu.org X-Migadu-Queue-Id: DE12D1E642 X-Spam-Score: -2.91 X-Migadu-Scanner: scn0.migadu.com X-TUID: lf1y4J7quPK9 Hi, raid5atemyhomework skribis: > Now, let us combine this with the second feature (really a bug): GNU > shepherd is a simple, single-threaded Scheme program. That means that > if the single thread enters an infinite loop (because of a Shepherd > service description that entered an infinite loop), then Shepherd > itself hangs. You=E2=80=99re right that it=E2=80=99s an issue; in practice, it=E2=80=99s = okay because we pay attention to the code we run there, but obviously, mistakes could lead to the situation you describe. It=E2=80=99s a known problem and there are plans to address it, discussed on this list a few times before. The Shepherd =E2=80=9Crecently=E2=80=9D swit= ched to =E2=80=98signalfd=E2=80=99 for signal handling in the main loop, with an ey= e on making the whole loop event-driven: https://issues.guix.gnu.org/41507 This will address this issue and unlock things like =E2=80=9Csocket activat= ion=E2=80=9D. That said, let=E2=80=99s not lie to ourselves: the Shepherd=E2=80=99s desig= n is simplistic. I think that=E2=80=99s okay though because there=E2=80=99s a w= ay to address the main issues while keeping it simple. Thanks, Ludo=E2=80=99.