Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Date: Thu, 15 Jun 2017 21:28:00 +0000 (UTC)
From: "Karan Mehta (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.13059477.1490638937000.28119.1497562080121@Atlassian.JIRA>
In-Reply-To: <JIRA.13059477.1490638937000@Atlassian.JIRA>
References: <JIRA.13059477.1490638937000@Atlassian.JIRA> <JIRA.13059477.1490638937683@jira-lw-us.apache.org>
Subject: [jira] [Commented] (HDFS-11583) Parent spans are not initialized to
 NullScope for every DFSPacket
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
archived-at: Thu, 15 Jun 2017 21:28:05 -0000


    [ https://issues.apache.org/jira/browse/HDFS-11583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16051089#comment-16051089 ] 

Karan Mehta commented on HDFS-11583:
------------------------------------

Thank you [~ajisakaa] and [~iwasakims]!

> Parent spans are not initialized to NullScope for every DFSPacket
> -----------------------------------------------------------------
>
>                 Key: HDFS-11583
>                 URL: https://issues.apache.org/jira/browse/HDFS-11583
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: tracing
>    Affects Versions: 2.7.1
>            Reporter: Karan Mehta
>            Assignee: Masatake Iwasaki
>             Fix For: 2.7.4
>
>         Attachments: HDFS-11583-branch-2.7.001.patch, HDFS-11583-branch-2.7.002.patch, HDFS-11583-branch-2.7.003.patch
>
>
> The issue was found while working with PHOENIX-3752.
> Each packet received by the {{run()}} method of {{DataStreamer}} class, uses the {{parents}} field of the {{DFSPacket}} to create a new {{dataStreamer}} span, which in turn creates a {{writeTo}} span as its child span. The parents field is initialized when the packet is added to the {{dataQueue}} and the value is initialized from the {{ThreadLocal}}. This is how HTrace handles spans. 
> A {{TraceScope}} is created and initialized to {{NullScope}} before the loop which runs till the point when the stream is closed. 
> Consider the following scenario, when the {{dataQueue}} contains multiple packets, only the first of which has a tracing enabled. The scope is initialized to the {{dataStreamer}} scope and a {{writeTo}} span is created as its child, which gets closed once the packet is sent out to a remote datanode. Before {{writeTo}} span is started, the {{dataStreamer}} scope is detached. So calling the close method on it doesn't do anything at the end of loop. 
> The second iteration will be using the stale value of the {{scope}} variable with a DFSPacket on which tracing is not enabled. This results in generation of an orphan {{writeTo}} spans which are being delivered to the {{SpanReceiver}} as registered in the TraceFramework. This may result in unlimited number of spans being generated and sent out to receiver. 


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

---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org