Hld
System Design
Medium
CartHold: High-Concurrency Reservation
Build a reservation system for high-demand e-commerce 'drops'. Users can hold an item in their cart for 10 minutes. The system must support 1 million concurrent users and strictly prevent overselling of limited inventory (e.g., 5,000 units) while maintaining low latency for 'add-to-cart' actions.
Key concepts
distributed lockingtransactional integrityhot-key management
Practise this out loud — free
Start a mock interview on THIS exact question — a voice AI interviewer opens with it, pushes back like a real onsite, then hands you an instant scorecard.
🎙 Practise this question now