[jira] [Created] (MESOS-422) Master leader election should be more robust to stale ephemeral nodes

["Bill Farner (JIRA)" <ji...@apache.org>]

Bill Farner created MESOS-422:
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             Summary: Master leader election should be more robust to stale ephemeral nodes
                 Key: MESOS-422
                 URL: https://issues.apache.org/jira/browse/MESOS-422
             Project: Mesos
          Issue Type: Bug
          Components: master
            Reporter: Bill Farner
            Priority: Minor


When a leading master exits abruptly, it may fatefully restart and think it's the leader.  If particularly unlucky, this could result in a set of masters that are indefinitely unstable.

Sequence of events:
- Master process becomes leader
- Master process exits, session expiration counter begins
- Master process restarts, reads leader node contents, and decides it's the leader (based on PID equality)
- Previous master session expires, node is deleted
- Master decides a different master is leader, commits suicide
- Rinse, repeat for newly-created master node

The salient fact here is that leaders should be concerned with "did i create the leader node" (ignoring node data) while clients want to be apprised of leader's node data.

Relevant code:
https://github.com/apache/mesos/blob/trunk/src/detector/detector.cpp#L548

ZK leader election recipe, for reference:
http://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection



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