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 9700D10241 for ; Thu, 19 Feb 2015 16:17:24 +0000 (UTC) Received: (qmail 47680 invoked by uid 500); 19 Feb 2015 16:17:11 -0000 Delivered-To: apmail-cassandra-commits-archive@cassandra.apache.org Received: (qmail 47628 invoked by uid 500); 19 Feb 2015 16:17:11 -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 47616 invoked by uid 99); 19 Feb 2015 16:17:11 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 19 Feb 2015 16:17:11 +0000 Date: Thu, 19 Feb 2015 16:17:11 +0000 (UTC) From: "Marcus Eriksson (JIRA)" To: commits@cassandra.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (CASSANDRA-8833) Stop opening compaction results early 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-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14327685#comment-14327685 ] Marcus Eriksson commented on CASSANDRA-8833: -------------------------------------------- bq. SSTableReader lifecycles are still approximately as complex due to index summary redistribution. Don't see how that can be as complex as we don't open early, move starts or shadow any files when doing this > Stop opening compaction results early > ------------------------------------- > > Key: CASSANDRA-8833 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8833 > Project: Cassandra > Issue Type: Improvement > Reporter: Marcus Eriksson > Fix For: 2.1.4 > > > We should simplify the code base by not doing early opening of compaction results. It makes it very hard to reason about sstable life cycles since they can be in many different states, "opened early", "starts moved", "shadowed", "final", instead of as before, basically just one (tmp files are not really 'live' yet so I don't count those). The ref counting of shared resources between sstables in these different states is also hard to reason about. This has caused quite a few issues since we released 2.1 > I think it all boils down to a performance vs code complexity issue, is opening compaction results early really 'worth it' wrt the performance gain? The results in CASSANDRA-6916 sure look like the benefits are big enough, but the difference should not be as big for people on SSDs (which most people who care about latencies are) > WDYT [~benedict] [~jbellis] [~iamaleksey] [~JoshuaMcKenzie]? -- This message was sent by Atlassian JIRA (v6.3.4#6332)