First of all, thanks for your time and quick response.
I'm not completely sure I understood your example, but is this what you
mean:
- Sink processes A, B, C
- Checkpoint persisted with A, B, C
- Notify checkpoint starts
- Notify checkpoints ACKs A
- Notify checkpoints ACKs B
- Job crashes
- Job
The acknowledgement has to be synchronous since Flink assume that after
notifyCheckpointComplete() all data has been persisted to external
systems. For example, if record 1 to 100 were passed to the sink and a
checkpoint occurs and completed, on restart Flink would continue with
record 101. But
