[GitHub] flink issue #2410: [FLINK-4449] [cluster management] Heartbeat Manager betwe...

[tillrohrmann <gi...@git.apache.org>]

Github user tillrohrmann commented on the issue:

    https://github.com/apache/flink/pull/2410
  
    Thanks for the contribution @beyond1920. The implementation of the `HeartbeatScheduler` goes in the right direction so that it is reusable :-) The testing is also better. However, we're still mixing different things in this PR (e.g. parts of the slot requesting logic).
    
    I think we can further generalize the heartbeating since the heartbeat manager is another component which should be reusable across components (e.g. for the JobManager to heartbeat the TMs). Furthermore, the receiving end of the heartbeating is not properly defined. 
    
    I think it would be best if we first properly define how this should look like. For example, I'm not sure whether the exponential backoff strategy is the right way to go since it can happen that you wait twice as long as you've defined until you're notified about a heartbeat failure. Another question is whether every heartbeat connection should be responsible for triggering itself or whether the heartbeat manager should be responsible for that. Then we have to define the receiving end. Is the heartbeat receiving end an independent `RpcEndpoint`? How does the payload delivery works? Does the sender side asks for the result (future) or does the receiving side answers via a tell message to the heartbeat manager?
    
    I've created an issue where we should continue the discussion https://issues.apache.org/jira/browse/FLINK-4478.


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