[HDFS-197] "du" fails on Cygwin

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed

Environment

Windows + Cygwin

• Assignee: Unassigned
• Reporter: Kohsuke Kawaguchi
• Created: 15/Mar/09 17:22
• Updated: 21/Jul/14 21:54
• Resolved: 21/Jul/14 21:54

Description

When I try to run a datanode on Windows, I get the following exception:

java.io.IOException: Expecting a line not the end of stream
	at org.apache.hadoop.fs.DU.parseExecResult(DU.java:181)
	at org.apache.hadoop.util.Shell.runCommand(Shell.java:179)
	at org.apache.hadoop.util.Shell.run(Shell.java:134)
	at org.apache.hadoop.fs.DU.<init>(DU.java:53)
	at org.apache.hadoop.fs.DU.<init>(DU.java:63)
	at org.apache.hadoop.hdfs.server.datanode.FSDataset$FSVolume.<init>(FSDataset.java:325)
	at org.apache.hadoop.hdfs.server.datanode.FSDataset.<init>(FSDataset.java:681)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.startDataNode(DataNode.java:291)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.<init>(DataNode.java:205)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1238)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1193)

This is because Hadoop execs "du -sk C:\tmp\hadoop-SYSTEM\dfs\data" with a Windows path representation, which cygwin du doesn't understand.

C:\hudson>du -sk C:\tmp\hadoop-SYSTEM\dfs\data
du -sk C:\tmp\hadoop-SYSTEM\dfs\data
du: cannot access `C:\\tmp\\hadoop-SYSTEM\\dfs\\data': No such file or directory

For this to work correctly, Hadoop would have to run cygpath first to get a Unix path representation, then to call DU.

Also, I had to use the debugger to get this information. Shell.runCommand should catch IOException from parseExecResult and add the buffered stderr to simplify the error diagnostics.

Issue Links

• is related to: MAPREDUCE-401 du fails on Ubuntu in TestJobHistory