[HDFS-2947] HA: On startup NN throws an NPE in the metrics system

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: HA branch (HDFS-1623)
• Fix Version/s: HA branch (HDFS-1623)
• Component/s: ha, namenode
• Target Version/s: HA branch (HDFS-1623)
• Hadoop Flags: Reviewed
• Assignee: Aaron Myers
• Reporter: Aaron Myers
• Created: 14/Feb/12 00:53
• Updated: 14/Feb/12 12:55
• Resolved: 14/Feb/12 08:42

Description

HDFS-2510 added some HA-specific metrics which check the NN's HAState. The NN initializes its HAState after the metrics are initialized, and thus we might hit an NPE during NN startup. This seems to be innocuous in that the NN's metrics still function, but it's poor form to log an unnecessary NPE.