Distributed Cache (Walnut Cache: Slots, Replication, Failover, Eviction)
Design your own distributed in-memory cache that holds 530 GB, serves a million operations a second, and keeps serving when a server or a whole zone fails.
The Engineering Career Operating System
More than interview prep. Your path forks at Senior, into building (IC) or leading (management). Pick a goal, see the real bar, and follow the exact path to get there.
Built by Staff Engineers, Principal Engineers, and Engineering Leaders who've built systems, led teams, and hired engineers.
The bar for each level is the real one, not generic advice.
A Prometheus blackbox probe checks the real checkout path every 5 seconds. Users see 10 second outages daily, yet no alert has ever fired. You made the probe also test the database and payment calls, and still nothing.
Why does the alert never fire?
Pick one. If it is wrong, you will see why, and you can try again.
Pick a level and be honest. Could you actually answer each of these out loud, right now? If several are shaky, that is the gap, and that is exactly what the path is for.
The bar: Design across services, make and defend trade-offs, and lead a design review.
If several are shaky, you are probably not there yet. Here is the path.
See the Senior Engineer pathWhether you are building LLM systems or getting grilled on them, go deep: the foundations, the engineering, the security, and the AI system design round. Read a full lesson free before you decide.
Now we also crack a few walnuts out loud, on video. Everything here stays right where it is.