Return-Path: X-Original-To: archive-asf-public-internal@cust-asf2.ponee.io Delivered-To: archive-asf-public-internal@cust-asf2.ponee.io Received: from cust-asf.ponee.io (cust-asf.ponee.io [163.172.22.183]) by cust-asf2.ponee.io (Postfix) with ESMTP id 7D667200B87 for ; Mon, 19 Sep 2016 21:58:23 +0200 (CEST) Received: by cust-asf.ponee.io (Postfix) id 7BFA5160ADC; Mon, 19 Sep 2016 19:58:23 +0000 (UTC) Delivered-To: archive-asf-public@cust-asf.ponee.io Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by cust-asf.ponee.io (Postfix) with SMTP id C0F1B160ABB for ; Mon, 19 Sep 2016 21:58:22 +0200 (CEST) Received: (qmail 12168 invoked by uid 500); 19 Sep 2016 19:58:21 -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 12139 invoked by uid 99); 19 Sep 2016 19:58:21 -0000 Received: from arcas.apache.org (HELO arcas) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 19 Sep 2016 19:58:21 +0000 Received: from arcas.apache.org (localhost [127.0.0.1]) by arcas (Postfix) with ESMTP id 5042D2C0D58 for ; Mon, 19 Sep 2016 19:58:21 +0000 (UTC) Date: Mon, 19 Sep 2016 19:58:21 +0000 (UTC) From: "sankalp kohli (JIRA)" To: commits@cassandra.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (CASSANDRA-12668) Memtable Contention in 2.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 archived-at: Mon, 19 Sep 2016 19:58:23 -0000 [ https://issues.apache.org/jira/browse/CASSANDRA-12668?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15504501#comment-15504501 ] sankalp kohli commented on CASSANDRA-12668: ------------------------------------------- By "always synchronous" I assume you mean always locking instead of using CAS? We did a test where you always write to a few CQL partition simultaneous to create contention. We have seen 2.0 has a higher throughput than 2.1 and looking at allocation points to this memtable issue. Then we made the configuration changes added in 7546 to always lock and that reduced the throughput. Looking at the heap dumps did not point that memtable is smaller in 2.1 vs 2.0. So I dont think this is an issue. Apart from the testing, the only clusters this is an issue is where we have contention and hence this is change is an issue. > Memtable Contention in 2.1 > -------------------------- > > Key: CASSANDRA-12668 > URL: https://issues.apache.org/jira/browse/CASSANDRA-12668 > Project: Cassandra > Issue Type: Bug > Reporter: sankalp kohli > > We added a new Btree implementation in 2.1 which causes write performance to go down in Cassandra if there is lot of contention in the memtable for a CQL partition. Upgrading a cluster from 2.0 to 2.1 with contention causes the cluster to fall apart due to GC. We tried making the defaults added in CASSANDRA-7546 configurable but that did not help. Is there anyway to fix this issue? -- This message was sent by Atlassian JIRA (v6.3.4#6332)