Current state: Accepted
Discussion thread: here
Vote thread: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Window size is not passed to the Kafka consumer during windowed aggregations, so the consumer uses the default Long.MAX_VALUE when initializing the deserializer. Both TimeWindowedSerde and TimeWindowedDeserializer have a default constructor that does not require a window size, causing fatal errors at runtime for some programs.
In StreamsConfig.java add window.size.ms
Deprecate the following methods
Log an error message in Serdes.scala for implicit def timeWindowedSerde and pass through to the deserializer
Add window.size.ms to the StreamsConfigs class to ensure that the desired window size is set when the consumer creates the TimeWindowedDeserializer instance. This is relevant for consuming TimeWindowed records directly, which is helpful when testing windowed aggregations. Without this change, all windows will have a size and end time of Long.MAX_VALUE. Users can either set the window size through the config or set the window size through the constructor. To help enforce this, the window.size.ms will not have a default value.
Additionally, deprecate constructors in both TimeWindowedDeserializer and WindowedSerdes that don't require a window size. This ensures that the window size would be properly set before encountering any instances where it should be used. When these are deprecated, the timeWindowedSerde implicit in Serdes.scala will be updated to log an error message explaining that this implicit should no longer be used. To keep backwards compatibility, this implicit won't be deprecated but will pass through to the deserializer.
Note that to use the windows.size.ms config through the console consumer (if desired), add the key.deserializer prefix and pass it in as a property.
Compatibility, Deprecation, and Migration Plan
Tests that need to be updated:
Classes that need to be updated: