Return-Path: X-Original-To: apmail-accumulo-notifications-archive@minotaur.apache.org Delivered-To: apmail-accumulo-notifications-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 94289112E2 for ; Fri, 16 May 2014 22:39:01 +0000 (UTC) Received: (qmail 73607 invoked by uid 500); 16 May 2014 11:19:53 -0000 Delivered-To: apmail-accumulo-notifications-archive@accumulo.apache.org Received: (qmail 23847 invoked by uid 500); 16 May 2014 11:06:05 -0000 Mailing-List: contact notifications-help@accumulo.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: jira@apache.org Delivered-To: mailing list notifications@accumulo.apache.org Received: (qmail 84314 invoked by uid 99); 16 May 2014 10:52:42 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 16 May 2014 10:52:42 +0000 Date: Fri, 16 May 2014 10:52:42 +0000 (UTC) From: "Keith Turner (JIRA)" To: notifications@accumulo.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Assigned] (ACCUMULO-2766) Single walog operation may wait for multiple hsync calls 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/ACCUMULO-2766?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Keith Turner reassigned ACCUMULO-2766: -------------------------------------- Assignee: Keith Turner > Single walog operation may wait for multiple hsync calls > -------------------------------------------------------- > > Key: ACCUMULO-2766 > URL: https://issues.apache.org/jira/browse/ACCUMULO-2766 > Project: Accumulo > Issue Type: Bug > Components: tserver > Affects Versions: 1.5.0, 1.5.1, 1.6.0 > Reporter: Keith Turner > Assignee: Keith Turner > Labels: performance > Fix For: 1.5.2, 1.6.1 > > Attachments: ACCUMULO-2677-1.patch > > > While looking into slow {{hsync}} calls, I noticed an oddity in the way Accumulo processes syncs. Specifically the way {{closeLock}} is used in {{DfsLogger}}, it seems like the following situation could occur. > > # thread B starts executing DfsLogger.LogSyncingTask.run() > # thread 1 enters DfsLogger.logFileData() > # thread 1 writes to walog > # thread 1 locks _closeLock_ > # thread 1 adds sync work to workQueue > # thread 1 unlocks _closeLock_ > # thread B takes sync work off of workQueue > # thread B locks _closeLock_ > # thread B calls sync > # thread 3 enters DfsLogger.logFileData() > # thread 3 writes to walog > # thread 3 blocks locking _closeLock_ > # thread 4 enters DfsLogger.logFileData() > # thread 4 writes to walog > # thread 4 blocks locking _closeLock_ > # thread B unlocks _closeLock_ > # thread 4 locks _closeLock_ > # thread 4 adds sync work to workQueue > # thread B takes sync work off of workQueue > # thread B blocks locking _closeLock_ > # thread 4 unlocks _closeLock_ > # thread B locks _closeLock_ > # thread B calls sync > # thread B unlocks _closeLock_ > # thread 3 locks _closeLock_ > # thread 3 adds sync work to workQueue > # thread 3 unlocks _closeLock_ > In this situation thread 3 unnecessarily has to wait for an extra {{hsync}} call. Not sure if this situation actually occurs, or if it occurs very frequently. Looking at the code it seems like it would be nice if sync operations could be queued w/o synchronizing w/ sync operations. -- This message was sent by Atlassian JIRA (v6.2#6252)