Software Engineer · Phone Screen · Coding

Netflix — Software Engineer ❌ Failed

Level: Unknown Level

Round: Phone Screen · Type: Coding · Difficulty: 7/10 · Duration: 60 min · Interviewer: Unfriendly

Topics: Caching, LRU Cache, Concurrency, API Design

Location: Los Gatos, CA

Interview date: 2025-08-15

Got offer: False

Summary

I had a technical phone screen where I needed to implement a key-value cache with expiration. First, I implemented lazy deletion and discussed how to avoid out-of-memory errors. Then I had to create another thread to delete expired data and discuss how to handle fixed size requirements using LRU. Finally, we discussed API design.

Details

The coding question I received was to implement an expiring key-value cache.

My Approach:

1. I started with a lazy deletion implementation.
2. Then, we discussed how to prevent out-of-memory (OOM) errors.
3. I was asked to create a separate thread to remove expired data.
4. We discussed how to handle a fixed size cache using the Least Recently Used (LRU) eviction policy.
5. Finally, we discussed the design of the API.

Key Insights:

• Understanding different cache eviction strategies is crucial.
• Considerations around concurrency and thread safety are important for cache implementations.
• API design for a cache should be intuitive and flexible.