Tsz Wo Nicholas Sze created HDFS-8254:
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             Summary: In StripedDataStreamer, it is hard to tolerate datanode 
failure in the leading streamer
                 Key: HDFS-8254
                 URL: https://issues.apache.org/jira/browse/HDFS-8254
             Project: Hadoop HDFS
          Issue Type: Sub-task
            Reporter: Tsz Wo Nicholas Sze
            Assignee: Tsz Wo Nicholas Sze


StripedDataStreamer javadoc is shown below.
{code}
 * The StripedDataStreamer class is used by {@link DFSStripedOutputStream}.
 * There are two kinds of StripedDataStreamer, leading streamer and ordinary
 * stream. Leading streamer requests a block group from NameNode, unwraps
 * it to located blocks and transfers each located block to its corresponding
 * ordinary streamer via a blocking queue.
{code}
Leading streamer is the streamer with index 0.  When the datanode of the 
leading streamer fails, the other steamers cannot continue since no one will 
request a block group from NameNode anymore.



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