What is the difference between sticky and cooperative sticky partition assignment?

Classic Sticky Assignor: minimizes partition movement on rebalance but still uses the eager (stop-the-world) protocol — all consumers stop, all assignments revoked, then redistributed. Cooperative Sticky Assignor (Kafka 2.4+): incremental rebalancing that only revokes partitions that need to move. Consumers that keep their partitions continue processing during rebalance. This dramatically reduces rebalance pause time. Use CooperativeStickyAssignor in all new deployments for better availability during scaling operations.

Expected key concepts: Sticky Assignor, Cooperative Sticky Assignor, eager protocol, stop-the-world, incremental rebalancing, revoke, continue processing, pause time, availability