[HDFS-4591] HA clients can fail to fail over while Standby NN is performing long checkpoint

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.4-alpha
• Fix Version/s: 2.1.0-beta
• Component/s: ha, namenode
• Target Version/s: 2.1.0-beta
• Hadoop Flags: Reviewed
• Assignee: Aaron Myers
• Reporter: Aaron Myers
• Created: 12/Mar/13 02:44
• Updated: 27/Aug/13 22:07
• Resolved: 13/Mar/13 19:56

Description

Clients know to fail over to talk to the Active NN when they perform an RPC to the Standby NN and it throws a StandbyException. However, most places in the code that check if the NN is in the standby state do so inside the FSNS fsLock. Since this lock is held for the duration of the saveNamespace during a checkpoint, StandbyExceptions will not be thrown during this time.