Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@cassandra.apache.org
Date: Thu, 14 Sep 2017 23:32:00 +0000 (UTC)
From: "Simon Zhou (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.13102421.1505431866000.118118.1505431920218@Atlassian.JIRA>
In-Reply-To: <JIRA.13102421.1505431866000@Atlassian.JIRA>
References: <JIRA.13102421.1505431866000@Atlassian.JIRA> <JIRA.13102421.1505431866124@jira-lw-us.apache.org>
Subject: [jira] [Created] (CASSANDRA-13877) Potential concurrency issue with
 CDC size calculation
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
archived-at: Thu, 14 Sep 2017 23:32:05 -0000

Simon Zhou created CASSANDRA-13877:
--------------------------------------

             Summary: Potential concurrency issue with CDC size calculation
                 Key: CASSANDRA-13877
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13877
             Project: Cassandra
          Issue Type: Bug
            Reporter: Simon Zhou
            Assignee: Simon Zhou


We're backporting CDC feature and bug fixes to 3.0. There is potential visibility issue with two variables CDCSizeTracker.sizeInProgress and DirectorySizeCalculator.size. They're declared as volatile however there are cases that when assigning new values to them, the new values depend on the current value. For example:
https://github.com/apache/cassandra/blob/e9da85723a8dd40872c4bca087a03b655bd2cacb/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManagerCDC.java#L285
https://github.com/apache/cassandra/blob/e9da85723a8dd40872c4bca087a03b655bd2cacb/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManagerCDC.java#L297

In rare cases we'll not be able to calculate CDC data size correctly. We should change these two variables back to AtomicLong, as the simplest fix. Java Concurrency In Practice section 3.1.3 explains well why we shouldn't use volatile in these two cases. I'll provide patch shortly.

cc [~JoshuaMcKenzie] [~jay.zhuang]


--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@cassandra.apache.org
For additional commands, e-mail: commits-help@cassandra.apache.org