From commits-return-149835-apmail-cassandra-commits-archive=cassandra.apache.org@cassandra.apache.org Mon Oct 26 18:48:37 2015 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 9D32418F56 for ; Mon, 26 Oct 2015 18:48:37 +0000 (UTC) Received: (qmail 47306 invoked by uid 500); 26 Oct 2015 18:48:28 -0000 Delivered-To: apmail-cassandra-commits-archive@cassandra.apache.org Received: (qmail 47196 invoked by uid 500); 26 Oct 2015 18:48:28 -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 47167 invoked by uid 99); 26 Oct 2015 18:48:27 -0000 Received: from arcas.apache.org (HELO arcas) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 26 Oct 2015 18:48:27 +0000 Received: from arcas.apache.org (localhost [127.0.0.1]) by arcas (Postfix) with ESMTP id C4D8E2C1F62 for ; Mon, 26 Oct 2015 18:48:27 +0000 (UTC) Date: Mon, 26 Oct 2015 18:48:27 +0000 (UTC) From: "Aaron Whiteside (JIRA)" To: commits@cassandra.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (CASSANDRA-9328) WriteTimeoutException thrown when LWT concurrency > 1, despite the query duration taking MUCH less than cas_contention_timeout_in_ms 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-9328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14974817#comment-14974817 ] Aaron Whiteside commented on CASSANDRA-9328: -------------------------------------------- If this is a known issue, and there is no other ticket to represent this issue, then please tell me again why you want to close it? This ticket should remain OPEN until the issue is resolved, regardless of the fact there is no known solution. And I don't see any documentation on this feature that says it will provide non-deterministic behavior under light (2 threads) contention. I disagree on your point that you can read the value after writing it to determine if the LWT was successful. You forget in a concurrent environment that this is the very definition of a race condition. With the current LWT implementation you can NEVER know 100% if an update succeeded or not. If you think this is not true please provide sample code on how to accomplish this.. if such a thing exists it should also be added to the official documentation as a work around on how to use LWT "correctly". > WriteTimeoutException thrown when LWT concurrency > 1, despite the query duration taking MUCH less than cas_contention_timeout_in_ms > ------------------------------------------------------------------------------------------------------------------------------------ > > Key: CASSANDRA-9328 > URL: https://issues.apache.org/jira/browse/CASSANDRA-9328 > Project: Cassandra > Issue Type: Bug > Components: Core > Reporter: Aaron Whiteside > Priority: Critical > Fix For: 2.1.x > > Attachments: CassandraLWTTest.java, CassandraLWTTest2.java > > > WriteTimeoutException thrown when LWT concurrency > 1, despite the query duration taking MUCH less than cas_contention_timeout_in_ms. > Unit test attached, run against a 3 node cluster running 2.1.5. > If you reduce the threadCount to 1, you never see a WriteTimeoutException. If the WTE is due to not being able to communicate with other nodes, why does the concurrency >1 cause inter-node communication to fail? -- This message was sent by Atlassian JIRA (v6.3.4#6332)