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Masatake Iwasaki commented on HDFS-11583: ----------------------------------------- bq. hadoop-2.7 depends on htrace-4 while hbase-1 depend on htrace-3. Sorry, that was wrong. I saw different version of code. hadoop-2.7 uses htrace-3. > Parent spans 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 > Reporter: Karan Mehta > > 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 (v6.3.15#6346) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org