I am implementing an kafka based application where I would like to manually acknowledge incoming messages. Architecture forces me to do it in a separate thread.
The question is: is it possible and safe to execute Acknowledgement.acknowledge() in a different thread than consumer?
Yes it is, as long as you use MANUAL and not MANUAL_IMMEDIATE, but I don't think you'll get what you expect.
Kafka doesn't track each message, just offsets within the partition.
Let's say message 1 arrives and you hand off to another thread. Then message 2 arrives and it is handed off to yet another thread.
When the offset for message 2 is ack'd, you are effectively acking both messages.
