What are the risks of using Recursion? (Stack Overflow, Exponential Time)

0-2 years experience

1. 1Suppose you need to compute the factorial of a number in a simple script. How would you implement it using recursion, and what could happen if the input is 20,000?
2. 2If you write a recursive function to traverse a binary tree, what will the call stack look like for a tree with depth 10,000? What risk does that pose?

2-5 years experience

1. 1You added a recursive depth‑first search to a feature that processes user‑generated graphs. After deploying, some users report the service crashes on large graphs. Walk me through how you'd debug this and what recursion‑related risks you’d consider.
2. 2Our team replaced an iterative loop with a recursive solution to simplify code, but performance degraded dramatically on worst‑case inputs. Explain why that might happen and how you'd decide which version to keep.

5-8 years experience

1. 1We have a microservice that parses nested JSON objects using recursion. Under heavy load, we see increased latency and occasional crashes. How would you redesign this component to mitigate recursion risks while preserving readability?
2. 2When building a compiler, we use recursive descent parsing. Discuss the trade‑offs of recursion depth limits and how you’d handle extremely deep or maliciously crafted inputs at scale.

8+ years experience

1. 1Our platform processes user‑defined formulas that can be arbitrarily nested. Currently we evaluate them with a recursive interpreter, leading to stack overflows in production. As a staff engineer, outline a migration plan to a safe, scalable evaluation engine, considering backward compatibility and team coordination.
2. 2A legacy codebase heavily relies on recursive algorithms for data processing across multiple services. Management wants to refactor to iterative approaches to improve reliability. How would you prioritize the refactor, assess impact, and convince stakeholders of the long‑term benefits?