Is there any attempt to keep adjacent shards together when spreading them out over multiple workers? In the documentation example it started with 1 worker/instance and 4 shards. Then auto-scaling occurred and a 2nd worker/instance was started up. The KCL auto-magically moved 2 shards over to worker 2. Is there any attempt at keeping adjacent shards together with a worker when autoscaling? What about when splitting shards?
Thanks
Random.
If you mean "Kinesis Consumer Application" as "Worker", then the consumer application with the most shards loses 1 shard to another application who has less shards.
"Lease" is the correct term here, it describes a consumer application & shard association. And there is not adjacency check for taking leases, it is pure random.
See source code, chooseLeaseToSteal method: https://github.com/awslabs/amazon-kinesis-client/blob/c6e393c13ec348f77b8b08082ba56823776ee48a/src/main/java/com/amazonaws/services/kinesis/leases/impl/LeaseTaker.java#L414