Sorry for late answer: A Kafka ack is not a signal that an individual message is complete, but that the message index pointer can move forwards. So if you read

Sorry for late answer: A Kafka ack is not a signal that an individual message is complete, but that the message index pointer can move forwards. So if you read 10 tasks and run them in parallel, you can't just ack a random selection of 5 as they complete. You could work out a system to ack the entire bunch when the last one finishes though. All of this assumes you're ok with more-than-once delivery, of course.