Category: system_design
Date: 2026-02-16
System Design Interview Practice Tool
1. Requirements (Functional + Non-functional)
Functional Requirements:
- User authentication and authorization
- Practice problem uploading and management (e.g., problem name, description, tags, difficulty level)
- User submission of solutions with code and execution result
- Practice problem categorization (e.g., by tags, difficulty level)
- Search functionality for practice problems
- User profile management (e.g., dashboard, practice problem history)
Non-functional Requirements:
- High availability and reliability
- Scalability to handle a large number of users and practice problems
- Performance: fast problem uploading, submission, and execution
- Security: protect user data and prevent cheating
- Maintainability: easy to modify and extend the system
2. High-Level Architecture
- Frontend: Client-side application built using JavaScript frameworks like React or Angular for a user-friendly interface
- Backend: Server-side application built using a language like Java, Python, or Node.js for API management, database interaction, and computation
- Database: Relational database like MySQL or PostgreSQL for storing user and practice problem data
- Message Queue: Distributed message queue like RabbitMQ or Apache Kafka for handling practice problem submissions and execution results
- API Gateway: API gateway like NGINX or Amazon API Gateway for API management and security
3. Database Design
- User Table: stores user information (e.g., username, email, password)
- Practice Problem Table: stores practice problem information (e.g., problem name, description, tags, difficulty level)
- Submission Table: stores user submission data (e.g., submission ID, user ID, practice problem ID, submission time)
- Execution Result Table: stores execution result data (e.g., execution ID, submission ID, execution time, result)
4. Scaling Strategy
- Horizontal Scaling: add more instances of the frontend, backend, and message queue services as needed
- Load Balancing: use a load balancer like HAProxy or Amazon ELB to distribute traffic across instances
- Caching: use a caching layer like Redis or Memcached to reduce database queries and improve performance
- Auto Scaling: use a cloud provider’s auto scaling feature to automatically add or remove instances based on traffic
5. Bottlenecks
- Database Performance: frequent database queries can lead to performance issues, consider caching and indexing
- Message Queue Processing: slow message queue processing can lead to delays in execution results, consider parallel processing and message queue optimization
- API Gateway Performance: high API gateway traffic can lead to performance issues, consider caching and load balancing
6. Trade-offs
- Security vs. Performance: balancing security and performance requirements, consider using a web application firewall (WAF) and load balancing
- Scalability vs. Complexity: balancing scalability and complexity requirements, consider using a microservices architecture and containerization
- Development Time vs. Maintenance Time: balancing development time and maintenance time requirements, consider using a framework like Django or Spring Boot
Solution using the First Principle of System Design
The first principle of system design is “Simplicity is the ultimate sophistication”. When designing the system, consider the following:
- Separate Concerns: separate the frontend, backend, and message queue services to improve maintainability and scalability
- Use Established Technologies: use established technologies and frameworks to reduce development time and improve reliability
- Prioritize Performance: prioritize performance and scalability requirements to ensure a high-quality user experience
- Monitor and Optimize: continuously monitor the system and optimize performance and scalability as needed