[HADOOP-8212] Improve ActiveStandbyElector's behavior when session expires

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.3, 0.24.0
• Fix Version/s: Auto Failover (HDFS-3042)
• Target Version/s: Auto Failover (HDFS-3042)
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 26/Mar/12 04:47
• Updated: 02/May/13 02:29
• Resolved: 29/Mar/12 21:48

Description

Currently when the ZK session expires, it results in a fatal error being sent to the application callback. This is not the best behavior – for example, in the case of HA, if ZK goes down, we would like the current state to be maintained, rather than causing either NN to abort. When the ZK clients are able to reconnect, they should sort out the correct leader based on the normal locking schemes.

Issue Links

• is depended upon by: HADOOP-8206 Common portion of ZK-based failover controller
• is part of: HDFS-3042 Automatic failover support for NN HA