From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-11.5 required=3.0 tests=AWL,BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id D12041F97E for ; Tue, 9 Oct 2018 17:38:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726481AbeJJA4Q (ORCPT ); Tue, 9 Oct 2018 20:56:16 -0400 Received: from mail-ed1-f48.google.com ([209.85.208.48]:35662 "EHLO mail-ed1-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726418AbeJJA4Q (ORCPT ); Tue, 9 Oct 2018 20:56:16 -0400 Received: by mail-ed1-f48.google.com with SMTP id y19-v6so2490939edd.2 for ; Tue, 09 Oct 2018 10:38:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7mwNdoo1fhI6dY3SvRc7t+1whVUzw1wrdVztjjzyzD0=; b=SHZL8AfZUhTJ2p/F9Nbr6qlOZoGxWuBvBWSgqWp5XDr83VZ5Ggh+hcuZibmfZwzSft 3SJ9S4lhl9rA3T28nwX1b4HOIxYIsHNfEjZiusB98iTkFuWlzKgCF550PBeVtMcDSou5 I3VEGhs8gyA3qTM21KWEokwYK05O+N+SbG03W4KoQZhKJbSD68l4KhYdNUNG01in6rMb CAJBKmbgdXUqPfCTlRbMTNrH6shdQmVT9jgfksL6Kj85tSa/NgDk9KtSbYt2HToj8yWi HJN4nfPSHrM3ueTRlq0/4htfa7S2570SS8o7vPmqq+WIaMn81Xikds7OZhqvGFrDrW3h bfUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7mwNdoo1fhI6dY3SvRc7t+1whVUzw1wrdVztjjzyzD0=; b=mQjrr+7JI6hiUOqbtwAtWMjP08BJvVvFZglpSAGURazkF8N77LlyxCBPW5vFxOV+DN 8rn959LPHeVASeLxR6Q/W6drss3jgVPru7lRO6J/jWG2Q5xG3ypeSDne8fH8D1zlrprj xLzLt8Fu+1XXxBYuYxVC+5pX9Awphdsf3/MRbNIEy112Qxqq+26QqkPaLnskugRDn1hh 5OFUH0vq7hoCfgjNWd6uPF+3eIqAt7xZFte0cLqXH4bKPBmlg5IVcsuoo+ENv1IcPTBH 0RITF3SoUuKLKLliO8ZlQRPpS7QrvSClIAQfMzNexoz+7sEujPwcn3M1ebZUhICfRbQb H/vQ== X-Gm-Message-State: ABuFfojyG55wJsZL8mLgkCAEBuvJsLoHKzbVvEDBf2hrj18So4Egac1d uE/Uug84W6LMmQ5BzCGos0QzynbFUtT31getJyLcaA== X-Google-Smtp-Source: ACcGV63FzLqolWFyXAVQesgE9LxxGMfPvVi9kxkWJ1owoKtyO3PxbiokaqFH6n684euNucpkXyfBhrwmkaD453HvASM= X-Received: by 2002:a50:bc12:: with SMTP id j18-v6mr15090030edh.154.1539106690927; Tue, 09 Oct 2018 10:38:10 -0700 (PDT) MIME-Version: 1.0 References: <7vr6lcj2zi.fsf@gitster.siamese.dyndns.org> <20070905074206.GA31750@artemis.corp> <87odgh0zn6.fsf@hades.wkstn.nix> <46DEF1FA.4050500@midwinter.com> <877in50y7p.fsf@hades.wkstn.nix> <87k1mta9x5.fsf@evledraar.gmail.com> In-Reply-To: From: Stefan Beller Date: Tue, 9 Oct 2018 10:37:59 -0700 Message-ID: Subject: Re: What's so special about objects/17/ ? To: Junio C Hamano Cc: =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= , nico@cam.org, Nick Alcock , koreth@midwinter.com, Linus Torvalds , git Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Mon, Oct 8, 2018 at 6:03 PM Junio C Hamano wrote: > > Stefan Beller writes: > > > On Sun, Oct 7, 2018 at 1:07 PM Junio C Hamano wrote: > >> > >> Junio C Hamano writes: > > > >> > ... > >> > by general public and I do not have to explain the choice to the > >> > general public ;-) > >> > >> One thing that is more important than "why not 00 but 17?" to answer > >> is why a hardcoded number rather than a runtime random. It is for > >> repeatability. > > > > Let's talk about repeatability vs statistics for a second. ;-) > > Oh, I think I misled you by saying "more important". > > I didn't mean that it is more important to stick to the "use > hardcoded value" design decision than sticking to "use 17". I've > made sure that everybody would understnd choosing any arbitrary byte > value other than "17" does not make the resulting Git any better nor > worse. Yes, I totally get that. We could have chosen 42 just because. > But discussing the design decision to use hardcoded value is > "more important", as that affects the balance between the end-user > experience and debuggability, and I tried to help those who do not > know the history by giving the fact that choice was made for the > latter and not for other hidden reasons, that those who would > propose to change the system may have to keep in mind. >From an end users point of view, the auto gc kicks in at random. (Maybe it's just me, but I don't keep track of the loose object count ;-) For debuggability, we could design a system that allows for debugging, e.g. "When GIT_AUTO_GC_BIN is set, use the number as set, otherwise take a random slot". > Sorry if you mistook it as if I were saying that it is important to > keep the design to use a hardcoded byte value. That wasn't what the > message was about. I understood very well that the choice of value was arbitrary and you do not have a convincing story as to why 17 (and not say 23, but such a story is not required, as all slots are equal from a design perspective). I do challenge the decision to take a hardcoded value, though, as it yields better properties for the end users IMHO, whereas debugging this specific case does not seem to be important to me.