[HADOOP-13824] FsShell can suppress the real error if no error message is present

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.7.1, 2.7.3
• Fix Version/s: 2.8.0, 3.0.0-alpha2
• Component/s: fs
• Labels: supportability
• Hadoop Flags: Reviewed
• Assignee: John Zhuge
• Reporter: Rob Vesse
• Created: 17/Nov/16 10:59
• Updated: 02/Oct/19 17:13
• Resolved: 09/Dec/16 23:47

Description

The FsShell error handling assumes in displayError() that the message argument is not null. However in the case where it is this leads to a NPE which results in suppressing the actual error information since a higher level of error handling kicks in and just dumps the stack trace of the NPE instead.

e.g.

Exception in thread "main" java.lang.NullPointerException
	at org.apache.hadoop.fs.FsShell.displayError(FsShell.java:304)
	at org.apache.hadoop.fs.FsShell.run(FsShell.java:289)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
	at org.apache.hadoop.fs.FsShell.main(FsShell.java:340)

This is deeply unhelpful because depending on what the underlying error was there may be no stack dumped/logged for it (as HADOOP-7114 provides) since FsShell doesn't explicitly dump traces for IllegalArgumentException which appears to be the underlying cause of my issue. Line 289 is where displayError() is called for IllegalArgumentException handling and that catch clause does not log the error.