Thank you for your response Piotr. I plan to upgrade to Flink 1.5.x early next year.
Two follow-up questions for now. 1. " When operator snapshots are taken, there are two parts: the synchronous and the asynchronous parts. " I understand that when the operator snapshot is being taken, the processing of that operator is stopped as taking this snapshot is synchronous part. Is there any other synchronous part in the snapshot / checkpoint process? 2. Based on the test I mentioned above, my understanding is that for a window operator, when all events that belongs to checkpoint N and the checkpoint barrier N are received by window operator (but pending for window to be triggered), then checkpoint barrier N will be immediately emitted to the sink operator (so snapshot can be completed) while the events are still pending to be evaluated by window operator. Can you please confirm my understanding as I was initially confused by the following second statement (emits all pending outgoing records) under Barriers section in this doc https://ci.apache.org/projects/flink/flink-docs-release-1.2/internals/stream_checkpointing.html ? "When an intermediate operator has received a barrier for snapshot n from all of its input streams, it emits itself a barrier for snapshot n into all of its outgoing streams." " Once the last stream has received barrier n, the operator emits all pending outgoing records, and then emits snapshot n barriers itself. " Thanks, Pranjal -- Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/
