[HDFS-2626] HA: BPOfferService.verifyAndSetNamespaceInfo needs to be synchronized

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: HA branch (HDFS-1623)
• Component/s: datanode, ha
• Target Version/s: HA branch (HDFS-1623)
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 03/Dec/11 05:14
• Updated: 24/Jan/12 23:51
• Resolved: 05/Dec/11 10:36

Description

When starting an HA blockpool with both namenodes up, I often see an NPE, referenced by one of the TODOs. The issue is the following interleaving:

• first BPActor registers, and sets bpNSInfo in BPOfferService. It then proceeds to initFsDataset which takes a little bit of time
• second BPActor registers, and sees bpNSInfo is non-null, then proceeds to heartbeat loop. Meanwhile BPActor 1 is still initting FSDataset
• second BPActor gets an NPE on first heartbeat since fsdataset is still null.
  We just need to synchronize that function to fix the NPE.