Design scalable inventory system and avoid races
System Design: Scalable, Highly Available Inventory Management
Design an inventory management system for a high-traffic e-commerce platform that tracks stock across multiple warehouses and supports real-time purchasing flows. The system must remain correct under high concurrency and flash-sale spikes.
Functional Requirements:
- Track inventory by product across multiple warehouses.
- Operations (all idempotent):
- Reserve: hold stock for an order with expiry (TTL).
- Release: free a reservation (manual or TTL expiry).
- Purchase: convert a reservation to a committed order and decrement available stock.
- Prevent overselling under concurrent requests.
- Emit order/inventory events with at-least-once delivery.
- Read endpoints:
- Get product availability (global total and per-warehouse breakdown).
Non-Functional Requirements:
- Flash-sale workload: ~50k RPS reads, ~5k RPS writes.
- High availability and horizontal scalability.
- Idempotent APIs; at-least-once events; exactly-once semantics at service boundaries where feasible.
Specify:
- Overall architecture (services, databases, caches, message buses).
- Data model (items, warehouses, reservations, versioning).
- Consistency model (strong vs eventual) with justification.
- Concurrency control and race-condition avoidance strategies (optimistic concurrency, conditional updates, idempotency keys, selective locks/quorum if needed).
- Scaling strategies (read replicas, sharding, write queues, CQRS).
- Cache design and invalidation.
- Handling of partial failures and retries.
- Exactly-once semantics at boundaries.
- Backpressure and rate limiting.
- Observability (metrics, tracing).
- Disaster recovery and multi-region considerations.
AI interview prep
Core dilemma
Balancing strict inventory consistency (preventing overselling) against high throughput and low latency requirements, especially during flash sales, while managing distributed state and potential race conditions.
3 tradeoffs and 2 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Design scalable inventory system and avoid races
System Design: Scalable, Highly Available Inventory Management
Design an inventory management system for a high-traffic e-commerce platform that tracks stock across multiple warehouses and supports real-time purchasing flows. The system must remain correct under high concurrency and flash-sale spikes.
Functional Requirements:
- Track inventory by product across multiple warehouses.
- Operations (all idempotent):
- Reserve: hold stock for an order with expiry (TTL).
- Release: free a reservation (manual or TTL expiry).
- Purchase: convert a reservation to a committed order and decrement available stock.
- Prevent overselling under concurrent requests.
- Emit order/inventory events with at-least-once delivery.
- Read endpoints:
- Get product availability (global total and per-warehouse breakdown).
Non-Functional Requirements:
- Flash-sale workload: ~50k RPS reads, ~5k RPS writes.
- High availability and horizontal scalability.
- Idempotent APIs; at-least-once events; exactly-once semantics at service boundaries where feasible.
Specify:
- Overall architecture (services, databases, caches, message buses).
- Data model (items, warehouses, reservations, versioning).
- Consistency model (strong vs eventual) with justification.
- Concurrency control and race-condition avoidance strategies (optimistic concurrency, conditional updates, idempotency keys, selective locks/quorum if needed).
- Scaling strategies (read replicas, sharding, write queues, CQRS).
- Cache design and invalidation.
- Handling of partial failures and retries.
- Exactly-once semantics at boundaries.
- Backpressure and rate limiting.
- Observability (metrics, tracing).
- Disaster recovery and multi-region considerations.