The New Way of Configuring Grace Periods for Windowed Operations in Kafka Streams

The grace period is a parameter of windowed operations such as Window or Session aggregates, or stream-stream joins. This configuration determines how long after a window ends any new data will still be processed. Events or records arriving after the expiration of the grace period are dropped from such windows. Prior to KIP-633, the default grace period was 24 hours which resulted in an endless stream of unexpected behaviors, problems, confusion and bewilderment for inexperienced users where results would not show up for 24 hours. In this talk, we cover the public API changes to the TimeWindows, SessionWindows, JoinWindows and SlidingWindows as well as the new guidance going forward.