Software Engineer II - Machine Learning

Uber

Let's explore a common coding challenge: implementing a thread-safe singleton in Java. A singleton, as you know, ensures that only one instance of a class exists and provides a global point of access to it. In a multithreaded environment, however, creating a singleton requires careful synchronization to prevent multiple instances from being created simultaneously. Consider different approaches like eager initialization, lazy initialization, and the double-checked locking pattern. Discuss the pros and cons of each approach, paying close attention to potential issues like race conditions and performance overhead. Then, write a Java class that implements a thread-safe singleton using the double-checked locking pattern with necessary synchronization to avoid race conditions. The singleton class should have a private constructor to prevent external instantiation and a static method getInstance() to provide access to the single instance. Show the code that demonstrates how multiple threads can safely access the singleton instance concurrently without creating multiple instances. Finally, explain why the double-checked locking pattern, when implemented correctly, offers a good balance between performance and thread safety in creating singletons.

Uber

System Design: Google Calendar Let's design a system similar to Google Calendar. Consider the following requirements: Functionality: Users should be able to create, read, update, and delete (CRUD) events. Events should have a title, description, start time, end time, location, and attendees. Recurring Events: Support recurring events (e.g., daily, weekly, monthly) with options for specifying exceptions (e.g., skip a specific instance). Invitations and Notifications: Users should be able to invite other users to events. Invited users should receive notifications about new events, updates, and cancellations. Implement a notification system, detailing frequency and method (e.g., email, push notification). Reminders: Users should be able to set reminders for events (e.g., 10 minutes before, 1 hour before). Time Zones: The system must correctly handle events across different time zones. Availability: Users should be able to view the availability of other users when scheduling events (free/busy). Scalability: The system should be able to handle a large number of users and events, ensuring responsiveness and reliability. How would you scale the system to accommodate millions of users and concurrent events? Consistency: Ensure data consistency across different users' views of the same event. Conflict Resolution: Address how to handle conflicting events and notify users accordingly. Specifically address these points in your design: Data model: How would you represent events, users, and their relationships in a database? API design: What API endpoints would you provide for creating, reading, updating, and deleting events? Concurrency and locking: How would you handle concurrent access to events to prevent data corruption? Notification system: How would you implement the notification system for event invitations, updates, and reminders? Scalability strategies: What strategies would you use to scale the system to handle a large number of users and events? Conflict Detection: How will the system determine event conflicts, and what notification mechanisms will be in place?

Uber

🔥 Recently Asked

Why do you want to work at Uber? To help me best assess your fit, please provide specific examples that highlight your skills and motivations. Consider the following points in your response: Alignment with Uber's mission: How does Uber's mission of creating opportunity through movement resonate with you? Provide a specific example of how your personal or professional goals align with this mission. Interest in the technology: What aspects of Uber's technology stack or engineering challenges excite you? Have you worked with similar technologies before? For instance, are you intrigued by the complexities of real-time mapping, large-scale data processing, or mobile app development? Company culture: What do you know about Uber's culture, and why does it appeal to you? Perhaps you are drawn to the fast-paced environment, the focus on innovation, or the emphasis on teamwork. Share an example of how you thrive in a similar environment. Career growth: How do you see this role contributing to your long-term career goals? What skills are you hoping to develop at Uber? For example, are you looking to gain experience in a particular domain, work on challenging projects, or mentor junior engineers? Previous experience: How does your previous experience make you a strong candidate for this role at Uber? Provide concrete examples of how you have demonstrated the skills and qualities that Uber values, such as problem-solving, communication, and leadership.