[HDFS-10940] Reduce performance penalty of block caching when not used

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.7.0
• Fix Version/s: 2.8.0, 3.0.0-alpha2
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Daryn Sharp
• Reporter: Daryn Sharp
• Created: 30/Sep/16 20:35
• Updated: 17/Oct/16 23:55
• Resolved: 03/Oct/16 16:47

Description

For every block location generated, the CacheManager will create a junk object for a hash lookup of cached locations. If there are no cached blocks, none of this is required.