Airbnb·Software Engineer·Technical Phone Screen·Senior

SeniorPrefer not to say

Apr 2026

Summary

Airbnb coding interview that centered on object-oriented design rather than pure algorithms. The main ask was building a Retryer class with a sensible default and room for extension, which sounds straightforward but the OOP angle trips you up if you're not thinking about it ahead of time.

Questions Asked (1)

Implement a Retryer class with a default retry strategy, and design it so that the behavior can be customized or extended.

System DesignTechnical Trade-offsAPI & Integrations

Author's notes

I started coding the default case pretty fast and that was fine, but then they pushed on extensibility and I kind of fumbled.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements: what operations need retrying, what exceptions to handle, and what customization is expected. Then design a Retryer class with a default strategy (e.g., exponential backoff with jitter) and use the Strategy pattern to allow custom retry policies, backoff algorithms, and exception handling. Finally, discuss trade-offs like idempotency, timeouts, and observability.

Pro tip: Emphasize that retries must be idempotent and that you'd include jitter to avoid thundering herd problems—this shows you understand production reliability concerns beyond just the code.

1. Clarify Requirements and Scope

Ask questions to understand what operations will be retried, what exceptions are retryable, and what customization points are needed (e.g., max attempts, backoff strategy, exception filters).

2. Define the Core Interface and Default Strategy

Design a Retryer class with a method like execute(Supplier<T>) that applies a default retry strategy (e.g., exponential backoff with jitter, max 3 attempts, retry on transient exceptions).

3. Enable Customization via Strategy Pattern

Introduce interfaces for RetryPolicy (decides whether to retry), BackoffStrategy (computes delay), and ExceptionClassifier (determines retryable exceptions). Allow these to be injected into the Retryer.

4. Discuss Trade-offs and Edge Cases

Address idempotency, timeout handling, circuit breaking, and observability (logging/metrics). Explain how the design supports these without over-engineering.

5. Provide a Usage Example and Extensibility

Show how a client can use the default Retryer or customize it with a custom backoff or exception filter, demonstrating the flexibility of the design.

Key Points to Mention

Strategy pattern for interchangeable retry policies and backoff algorithms
Default strategy: exponential backoff with jitter, capped attempts, retry on transient exceptions
Idempotency requirement for retried operations
Thread safety and statelessness of the Retryer
Observability: logging retries and emitting metrics
Avoiding retry storms via jitter and circuit breakers

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.