[HDFS-3974] dfsadmin -metasave throws NPE when under-replicated blocks are recently deleted

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.0.0-alpha1
• Component/s: namenode
• Assignee: Andy Isaacson
• Reporter: Todd Lipcon
• Created: 25/Sep/12 21:36
• Updated: 12/May/16 18:17

Description

We currently have the following race:

• Block is underreplicated, hence it's present in neededReplications
• User deletes the block - its BlockInfo.blockCollection is set to null
• Admin runs metaSave before the replication monitor runs.

This causes an NPE since block.getBlockCollection() for one of the neededReplication blocks has become null.

Issue Links

• duplicates: HDFS-4867 metaSave NPEs when there are invalid blocks in repl queue.