[jira] [Updated] (SAMZA-2597) Maintain traversal order for registered operators

["Bharath Kumarasubramanian (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SAMZA-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bharath Kumarasubramanian updated SAMZA-2597:
---------------------------------------------
    Priority: Minor  (was: Blocker)

> Maintain traversal order for registered operators
> -------------------------------------------------
>
>                 Key: SAMZA-2597
>                 URL: https://issues.apache.org/jira/browse/SAMZA-2597
>             Project: Samza
>          Issue Type: Bug
>            Reporter: Bharath Kumarasubramanian
>            Assignee: Bharath Kumarasubramanian
>            Priority: Minor
>
> *Problem*: Currently, we have a deterministic way of creating the operator DAG by having a LinkedHashMap so that during our runtime, we ensure the lifecycle of operators follow a deterministic order.
> While we use the same order to traverse the graph and create the DAG, we lose the order within the sub DAG as the registered operators is a HashSet. The implication is result of an operator is dispatched non-deterministically to its sub-DAG. i.e
> Op A --> Op B --> Op C
>        |--> Op D --> Op E
> Output of Op A can be dispatched to Op B or Op D depending how we iterate the `registeredOperators` set of Op A. 
> While this is not a guarantee Samza provides to applications, we want to be consistent with graph traversal order, DAG insertion order and DAG traversal order.
> *Change*: Use `LinkedHashSet` instead of `HashSet` to make it consistent.



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