Design a Ticketmaster-like ticketing system
MicrosoftSoftware Engineer · Onsite
Last updated
This problem tests your ability to design a high-concurrency reservation system that prevents overbooking while ensuring fairness and low latency during peak traffic.
Design a Ticketmaster-like Ticketing System
Design a backend service that allows users to browse events and purchase tickets. The system must handle massive spikes in traffic during "on-sale" events (e.g., popular concerts) without crashing or double-booking seats.
Requirements
Functional Requirements:
- Users can view event details and available seat maps.
- Users can select seats and place them in a temporary hold (e.g., 10 minutes) before purchasing.
- Users can complete a payment to finalize the purchase.
Non-Functional Requirements:
- High availability and scalability: Support millions of concurrent users during a ticket drop.
- Strong consistency: No two users should be able to book the same seat simultaneously.
- Performance: Low latency for seat selection and checkout processes.
Your Task
Provide a high-level architecture including:
- API Design: Define the core endpoints for viewing availability, holding a seat, and completing a payment.
- Data Model: Propose a database schema for Events, Seats, and Transactions, considering the choice between SQL and NoSQL.
- Concurrency Control: Explain how you will handle race conditions during the "seat hold" phase to prevent double-booking.
- Scalability: Describe strategies to handle read/write traffic during peak load (e.g., caching, queueing, database sharding).
Hints
Hint 1
Consider using a distributed locking mechanism or optimistic locking on the seat status to ensure that only one user can hold a specific seat at a time.
Hint 2
For massive traffic spikes, consider implementing a virtual waiting room or message queue to throttle incoming requests and protect the core database.
Hint 3
Use a cache like Redis for seat status tracking to offload read-heavy requests from the primary database while using a reliable store for final transactions.
Follow-up questions
- How would you integrate a third-party payment provider and handle cases where the payment succeeds but the database update fails?
- What specific measures would you implement to prevent bots from scraping seat availability or scalping tickets?
- How would you handle the 'event cleanup' process, such as releasing held seats that were never purchased?
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