SteNicholas opened a new pull request #13853:
URL: https://github.com/apache/flink/pull/13853
## What is the purpose of the change
*Currently, both sources and watermark/timestamp operators can emit
watermarks that we don't really need. We only need a final watermark in BATCH
execution mode. `TimestampsAndWatermarksOperator` should check whether to
periodically emit watermarks or only one final watermark at the end of input by
the runtime execution mode.*
## Brief change log
- *`TimestampsAndWatermarksOperator` adds `emitProgressiveWatermarks` to
check whether to periodically emit watermarks or only one final watermark at
the end of input by the runtime execution mode.*
- *`watermarkGenerator` in `TimestampsAndWatermarksOperator` periodically
calls the `onPeriodicEmit` method if `emitProgressiveWatermarks` is true.*
## Verifying this change
- *`periodicWatermarksEmitOnPeriodicEmit` and
`periodicWatermarksOnlyEmitOnPeriodicEmit` in
`TimestampsAndWatermarksOperatorTest` adds the test cases for the batch runtime
execution mode to verfiy whether to periodically emit watermarks in batch
execution mode.*
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (yes / **no**
/ don't know)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (yes / **no** /
don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (yes / **no**)
- If yes, how is the feature documented? (**not applicable** / docs /
JavaDocs / not documented)
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