From owner-freebsd-hackers@FreeBSD.ORG Mon Oct 10 19:19:14 2011 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 16556106564A; Mon, 10 Oct 2011 19:19:14 +0000 (UTC) (envelope-from brodbd@uw.edu) Received: from mail-ey0-f182.google.com (mail-ey0-f182.google.com [209.85.215.182]) by mx1.freebsd.org (Postfix) with ESMTP id 7813D8FC18; Mon, 10 Oct 2011 19:19:13 +0000 (UTC) Received: by eyd10 with SMTP id 10so1829083eyd.13 for ; Mon, 10 Oct 2011 12:19:12 -0700 (PDT) MIME-Version: 1.0 Received: by 10.213.3.209 with SMTP id 17mr346117ebo.120.1318272944278; Mon, 10 Oct 2011 11:55:44 -0700 (PDT) Received: by 10.213.112.130 with HTTP; Mon, 10 Oct 2011 11:55:44 -0700 (PDT) In-Reply-To: References: <20111004160043.GA16034@lpthe.jussieu.fr> <051853CE-03EC-4EEC-A5AC-C380131B28E4@gsoft.com.au> <4e8f073c.3g2aD/Zz9KdsWOKN%perryh@pluto.rain.com> Date: Mon, 10 Oct 2011 11:55:44 -0700 Message-ID: From: David Brodbeck To: Michael Bushkov Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Tom Evans , freebsd-hackers@freebsd.org, perryh@pluto.rain.com Subject: Re: Does anyone use nscd? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Oct 2011 19:19:14 -0000 On Fri, Oct 7, 2011 at 3:30 AM, Michael Bushkov wrote: > While I agree that nscd negative caching bug should be fixed, it won't > help with the problem that users encounter during ports installation. > When, for example, user "x" is added during port install, the > following steps are involved: > 1. Script checks if "x" is present in the users list. Nscd is queried, > it returns negative and caches negative answer. > 2. Script adds user "x". > 3. Script checks that "x" have indeed been added. Nscd is queried, > cachned negative answer is returned. Script fails as a result. > > So unless negative caching time is less than the time between steps 1) > and 3) the issues during ports installation will persist. Is there any reason to cache negative hits? It seems like you shouldn't see large volumes of them except in some fairly specific circumstances, like extracting a tarball as the root user with invalid UIDs. Maybe I'm missing something, but it seems like turning off negative caching would avoid a lot of potential problems for not much cost. -- David Brodbeck System Administrator, Linguistics University of Washington