Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/2696
That's a very good addition, we need something like that.
After an offline discussion with @tillrohrmann we came to the following
conclusion:
There is a tricky problem with that pure appraoch: When the JobManager
fails, all TaskManagers will "quarantine" that JobManager's actor system after
they detected the failure. That means they exit and restart. Effectively, a
JobManager failure results in all TaskManagers restarting.
That is a bit heavy.
Instead, we'll adjust this to do the following:
- TaskManagers must not watch the JobManager via Akka. That way,
JobManager failures do not cause any quarantining on the TaskManager side.
- The JobManager keeps watching the TaskManagers via Akka, so TaskManager
failures (false positives) still result in TaskManager quarantine, which means
the TaskManager need to restart when a TM-JM link breaks
How do TaskManagers then detect JobManager failure?
- TaskManagers send heartbeats to the JobManager anyways (accumulators,
in the future task status reconciliation). The TaskManagers use that to detect
JobManager failures.
- In high availability setups, TaskManagers notice JobManager failure
also via ZooKeeper
- In addition, in flip-6 the resource manager tells TaskManagers about
JobManager container failures
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