[HDFS-6047] TestPread NPE inside in DFSInputStream hedgedFetchBlockByteRange

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.4.0
• Hadoop Flags: Reviewed
• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 04/Mar/14 00:56
• Updated: 10/Apr/14 13:11
• Resolved: 04/Mar/14 21:15

Description

Our andrew.wang saw this on internal test cluster running trunk:

java.lang.NullPointerException: null
	at org.apache.hadoop.hdfs.DFSInputStream.hedgedFetchBlockByteRange(DFSInputStream.java:1181)
	at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1296)
	at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:78)
	at org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:108)
	at org.apache.hadoop.hdfs.TestPread.pReadFile(TestPread.java:151)
	at org.apache.hadoop.hdfs.TestPread.testMaxOutHedgedReadPool(TestPread.java:292)

TestPread was failing.

The NPE comes of our presuming there always a chosenNode as we set up hedged reads inside in hedgedFetchBlockByteRange (chosenNode is null'd each time through the loop). Usually there is a chosenNode but need to allow for case where there is not.