System designHardsd-g217

Subject CoordinationLevel Senior–Staff~45 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design the partition-assignment + rebalancing coordination for a consumer-group system processing a 2,000-partition event stream across an autoscaling pool of consumers (5–100 nodes). Each partition must be owned by exactly one consumer at a time, ownership must rebalance when nodes join/leave, and rebalancing must not cause a long global stop-the-world pause where no partitions are being processed. How do you assign partitions and minimize disruption during rebalances?

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

Loading whiteboard…

Run or narrate your approach, then ask the coach.