mynameborat opened a new pull request #1436: URL: https://github.com/apache/samza/pull/1436
**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. **Tests**: Added unit test to ensure insertion order is maintained during traversal **API Changes**: None **Usage Instructions**: None **Upgrade Instructions**: None ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
