[HDFS-7944] Minor cleanup of BlockPoolManager#getAllNamenodeThreads

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Target Version/s: 2.8.0
• Hadoop Flags: Reviewed
• Assignee: Arpit Agarwal
• Reporter: Arpit Agarwal
• Created: 17/Mar/15 18:53
• Updated: 30/Aug/16 01:38
• Resolved: 31/Mar/15 04:30

Description

BlockPoolManager#getAllNamenodeThreads can avoid unnecessary list to array conversion and vice versa by returning an unmodifiable list.

Since NN addition/removal is relatively rare we can just use a CopyOnWriteArrayList for concurrency.