Return-Path: X-Original-To: apmail-hadoop-hdfs-issues-archive@minotaur.apache.org Delivered-To: apmail-hadoop-hdfs-issues-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id C7D1F10AED for ; Mon, 23 Dec 2013 08:08:12 +0000 (UTC) Received: (qmail 98203 invoked by uid 500); 23 Dec 2013 08:07:58 -0000 Delivered-To: apmail-hadoop-hdfs-issues-archive@hadoop.apache.org Received: (qmail 98136 invoked by uid 500); 23 Dec 2013 08:07:54 -0000 Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: hdfs-issues@hadoop.apache.org Delivered-To: mailing list hdfs-issues@hadoop.apache.org Received: (qmail 98100 invoked by uid 99); 23 Dec 2013 08:07:52 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 23 Dec 2013 08:07:52 +0000 Date: Mon, 23 Dec 2013 08:07:52 +0000 (UTC) From: "Edward Bortnikov (JIRA)" To: hdfs-issues@hadoop.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (HDFS-5453) Support fine grain locking in FSNamesystem 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/HDFS-5453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13855489#comment-13855489 ] Edward Bortnikov commented on HDFS-5453: ---------------------------------------- Orthogonally to the recent thread ... Attached is a spreadsheet with simulation results that exemplify the ballpark gain from transitioning to a completely lock-free architecture. It is based on a very recent Hadoop 2.0 code. This is more of a long-term feature, which we believe is what the namenode ultimately needs. > Support fine grain locking in FSNamesystem > ------------------------------------------ > > Key: HDFS-5453 > URL: https://issues.apache.org/jira/browse/HDFS-5453 > Project: Hadoop HDFS > Issue Type: New Feature > Components: namenode > Affects Versions: 2.0.0-alpha, 3.0.0 > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Attachments: async_simulation.xlsx > > > The namesystem currently uses a course grain lock to control access. This prevents concurrent writers in different branches of the tree, and prevents readers from accessing branches that writers aren't using. > Features that introduce latency to namesystem operations, such as cold storage of inodes, will need fine grain locking to avoid degrading the entire namesystem's throughput. -- This message was sent by Atlassian JIRA (v6.1.5#6160)