[HDFS-1738] change hdfs jmxget to return an empty string instead of null when an attribute value is not available.

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Component/s: tools
• Hadoop Flags: Reviewed
• Assignee: Tanping Wang
• Reporter: Tanping Wang
• Created: 09/Mar/11 01:19
• Updated: 20/Apr/11 23:33
• Resolved: 22/Mar/11 17:38

Description

Currently the tool, hdfs jmx returns null in case of an attribute value is not available. A null pointer exception is thrown and the value of the rest attributes are not printed. It makes more sense to return an empty string and continue to print out the values for the rest attributes.

Example of current behavior
$ hdfs jmxget -server hostname.com -port 8004 -service NameNode,name=NameNodeActivity

>>>>>>>>jmx name: name=NameNodeActivity,service=NameNode
tag.ProcessName=NameNode
java.lang.NullPointerException
at org.apache.hadoop.hdfs.tools.JMXGet.printAllValues(JMXGet.java:106)
at org.apache.hadoop.hdfs.tools.JMXGet.main(JMXGet.java:329)