[HDFS-7899] Improve EOF error message

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Component/s: hdfs-client
• Hadoop Flags: Reviewed
• Assignee: Jagadesh Kiran N
• Reporter: Harsh J
• Created: 06/Mar/15 09:56
• Updated: 30/Aug/16 01:38
• Resolved: 06/Oct/15 10:27

Description

Currently, a DN disconnection for reasons other than connection timeout or refused messages, such as an EOF message as a result of rejection or other network fault, reports in this manner:

WARN org.apache.hadoop.hdfs.DFSClient: Failed to connect to /x.x.x.x:nnnn for block, add to deadNodes and continue. java.io.EOFException: Premature EOF: no length prefix available 
java.io.EOFException: Premature EOF: no length prefix available 
at org.apache.hadoop.hdfs.protocol.HdfsProtoUtil.vintPrefixed(HdfsProtoUtil.java:171) 
at org.apache.hadoop.hdfs.RemoteBlockReader2.newBlockReader(RemoteBlockReader2.java:392) 
at org.apache.hadoop.hdfs.BlockReaderFactory.newBlockReader(BlockReaderFactory.java:137) 
at org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:1103) 
at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:538) 
at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:750) 
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:794) 
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:602) 

This is not very clear to a user (warn's at the hdfs-client). It could likely be improved with a more diagnosable message, or at least the direct reason than an EOF.