Return-Path: X-Original-To: apmail-cassandra-commits-archive@www.apache.org Delivered-To: apmail-cassandra-commits-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 69FAB105D5 for ; Wed, 20 Nov 2013 16:59:47 +0000 (UTC) Received: (qmail 36537 invoked by uid 500); 20 Nov 2013 16:59:38 -0000 Delivered-To: apmail-cassandra-commits-archive@cassandra.apache.org Received: (qmail 36468 invoked by uid 500); 20 Nov 2013 16:59:38 -0000 Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@cassandra.apache.org Delivered-To: mailing list commits@cassandra.apache.org Received: (qmail 36419 invoked by uid 99); 20 Nov 2013 16:59:37 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 20 Nov 2013 16:59:37 +0000 Date: Wed, 20 Nov 2013 16:59:37 +0000 (UTC) From: "Brandon Williams (JIRA)" To: commits@cassandra.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Updated] (CASSANDRA-6385) FD phi estimator initial conditions MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/CASSANDRA-6385?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Brandon Williams updated CASSANDRA-6385: ---------------------------------------- Reviewer: Brandon Williams Reproduced In: 2.0.2, 1.2.11, 1.2.9 (was: 1.2.9, 1.2.11, 2.0.2) > FD phi estimator initial conditions > ----------------------------------- > > Key: CASSANDRA-6385 > URL: https://issues.apache.org/jira/browse/CASSANDRA-6385 > Project: Cassandra > Issue Type: Bug > Components: Core > Reporter: Quentin Conner > > phi estimates are calculated for newly discovered nodes from an un-filled (new, uninitialized) deque. > The inter-arrival time (elapsed time between gossip heartbeats) is stored in the o.a.c.gms.ArrivalWindow.arrivalIntervale deque for each received heartbeat, up to the maximum window size of 1000 samples. > In the o.a.c.gms.FailureDetector.interpret() method, phi is calculated for the node which uses a statistical measure called variance. Like mean, variance on a population (a set of numbers or measurements) is not statistically relevant unless the population set size is 30 or greater. > When a new node is discovered, the calculated variance is higher than normal, and causes phi to be higher than normal, resulting in a false positive failure detection. -- This message was sent by Atlassian JIRA (v6.1#6144)