Walmart · Primly Community

Walmart senior / L5 system design interview, what to expect (just finished my loop)

remote_swe_42 · 4 replies

Did the Walmart Global Tech senior SWE loop last month. Five rounds total. Wanted to write up the system design portion because it's not what I expected coming from pure FAANG prep.

The round was 60 minutes with two engineers. One did most of the talking, the other took notes and asked maybe three questions the whole time.

The prompt. They gave me: "Design a real-time inventory tracking system for 4,000+ stores." Which, okay, very on-brand. But the actual focus wasn't on the clever distributed architecture, it was on the tradeoffs around consistency vs. availability, specifically: what happens when a store goes offline and inventory gets stale?

I went CAP theorem basics right away and they seemed happy with that framing. We spent probably 20 of the 60 minutes just talking through what "real-time" actually needs to mean for different consumers: a customer checking stock online vs. a store associate picking an order vs. a demand forecasting model. This was good. They explicitly said they care about how you scope ambiguity.

What mattered. Sketching a basic event-driven architecture (Kafka for inventory events, separate read store for the online layer) landed well. They pushed on: how do you handle a 10x spike during Black Friday? What's your rollback plan if a service fails mid-update? Definitely practice failure mode reasoning, not just the happy path.

I did not get asked about specific internal Walmart tech. They're running a lot of GCP and some Azure, but the design round was completely cloud-agnostic.

Level signal. For senior / principal track, they care that you drive the conversation, not just answer questions. I let a 5-minute silence happen early on because I was drawing, and I learned later the interviewers interpreted that as "comfortable with ambiguity" not awkwardness. Not sure if that's consistent across panels but worth noting.

Not going to say the round was harder or easier than a Google E5 or Amazon L5 equivalent. Different flavor. Walmart leans more practical (retail-ops context) and less CS-theory. If you're studying for this, think about distributed writes at retail scale and work backward from there.

4 replies

sre_sol

The 10x Black Friday question is extremely Walmart. Came up in both my phone screen and the onsite. They apparently have a whole internal postmortem culture around holiday scaling. If you can reference concepts like circuit breakers and graceful degradation, you're going to sound very on-topic.

hardware_hugo

Yes, graceful degradation came up explicitly. I said something like "we'd rather show possibly stale stock than show an error page" and they nodded along. Definitely have a position on that tradeoff.

finance_faye

Was the design round at the onsite or was there a separate system design phone screen first? Trying to figure out what to prep for which stage.

consultant_cam

System design was only at the onsite for me. The recruiter phone screen was all behavioral, and the HackerRank OA had no design component. So save the big system design prep for the loop itself.