Return-Path: X-Original-To: apmail-zookeeper-user-archive@www.apache.org Delivered-To: apmail-zookeeper-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 066139C25 for ; Mon, 14 Nov 2011 15:19:19 +0000 (UTC) Received: (qmail 92702 invoked by uid 500); 14 Nov 2011 15:19:18 -0000 Delivered-To: apmail-zookeeper-user-archive@zookeeper.apache.org Received: (qmail 92670 invoked by uid 500); 14 Nov 2011 15:19:18 -0000 Mailing-List: contact user-help@zookeeper.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@zookeeper.apache.org Delivered-To: mailing list user@zookeeper.apache.org Received: (qmail 92662 invoked by uid 99); 14 Nov 2011 15:19:18 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 14 Nov 2011 15:19:18 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of ted.dunning@gmail.com designates 209.85.161.170 as permitted sender) Received: from [209.85.161.170] (HELO mail-gx0-f170.google.com) (209.85.161.170) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 14 Nov 2011 15:19:12 +0000 Received: by ggnk4 with SMTP id k4so6481827ggn.15 for ; Mon, 14 Nov 2011 07:18:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=iGjwErBgtcZ9CoUfR9hy4EFgV4ME/9+BoXIwBeT1jjw=; b=u7UXq2tgNSUZ/hqEuRlPjatt6mm1FFkbwayrgN1SeiKui6C1S2QkJBAPDX++oUHrPv 4/iUjH+yqp8LM7QULeNtOdMFg75dxN6Dd2BK+jhwLIkRXONHY9+NQJxHtVatnlCbbCiK TfZENAld6n8lnHVA1sAM+/nbItmGVc+xJ1TLA= Received: by 10.50.17.199 with SMTP id q7mr23302297igd.20.1321283931082; Mon, 14 Nov 2011 07:18:51 -0800 (PST) MIME-Version: 1.0 Received: by 10.50.159.200 with HTTP; Mon, 14 Nov 2011 07:18:30 -0800 (PST) In-Reply-To: References: From: Ted Dunning Date: Mon, 14 Nov 2011 07:18:30 -0800 Message-ID: Subject: Re: Missing session state handling in most Leader Election implementations To: user@zookeeper.apache.org Content-Type: multipart/alternative; boundary=14dae9340ec35c0ef804b1b3630b --14dae9340ec35c0ef804b1b3630b Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable You should be good to go with a very aggressive session timeout. The lack of correct handling for disconnects should not hurt you and may actually help since there may be clients who can access the master who is partitioned away from the ZK cluster, but not access the newly elected master. On Mon, Nov 14, 2011 at 3:25 AM, J=C3=A9r=C3=A9mie BORDIER wrote: > Ted, can't add much to what you said, totally agree. We already > planned on having a watchdog on this anyway. Having several master for > a very short time wouldn't be a problem for us, but this must be an > ephemeral state. (We use master election to determine a single host > responsible of generating unique 64 bit IDs with the first 16 bits > dedicated to an incremental "master id", so when a new master gets > elected, the whole range changes. Having 2 masters for a few seconds > wouldn't be an issue as the IDs cannot overlap, but still that's > something we want to avoid as much as possible). > --14dae9340ec35c0ef804b1b3630b--