Edge case split-brain race in ZK-based auto-failover
----------------------------------------------------
Key: HADOOP-8217
URL: https://issues.apache.org/jira/browse/HADOOP-8217
Project: Hadoop Common
Issue Type: Bug
Components: ha
Affects Versions: 0.24.0
Reporter: Todd Lipcon
Assignee: Todd Lipcon
As discussed in HADOOP-8206, the current design for automatic failover has the
following race:
- ZKFC1 gets active lock
- ZKFC1 is about to send transitionToActive() and machine freezes (eg GC pause
+ swapping)
- ZKFC1 loses its ZK lock, ZKFC2 gets ZK lock
- ZKFC2 calls transitionToStandby on NN1, and transitions NN2 to active
- ZKFC1 wakes up from pause, calls transitionToActive(), now we have a bad
situation
This is rare, since it requires ZKFC1 to freeze longer than its ZK session
timeout, but worth fixing, since the results can be disastrous.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
