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Vinayakumar B commented on HDFS-7884: ------------------------------------- I think, its just a race between client-read and delete of the block. Safe option is to null-check and throw ReplicaNotFoundException {code} // Obtain a reference before reading data FsVolumeSpi volume = datanode.data.getVolume(block); if (volume == null) { // This is race b/n delete and read throw new ReplicaNotFoundException(block); } this.volumeRef = volume.obtainReference();{code} > NullPointerException in BlockSender > ----------------------------------- > > Key: HDFS-7884 > URL: https://issues.apache.org/jira/browse/HDFS-7884 > Project: Hadoop HDFS > Issue Type: Bug > Components: datanode > Reporter: Tsz Wo Nicholas Sze > Assignee: Brahma Reddy Battula > Priority: Blocker > Attachments: > org.apache.hadoop.hdfs.TestAppendSnapshotTruncate-output.txt > > > {noformat} > java.lang.NullPointerException > at > org.apache.hadoop.hdfs.server.datanode.BlockSender.<init>(BlockSender.java:264) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:506) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opReadBlock(Receiver.java:116) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:71) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:249) > at java.lang.Thread.run(Thread.java:745) > {noformat} > BlockSender.java:264 is shown below > {code} > this.volumeRef = datanode.data.getVolume(block).obtainReference(); > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)