Explain Circuit Breaker vs Retry.

A Circuit Breaker stops calls to a service after repeated failures to prevent cascading outages, while a Retry automatically reattempts an operation to recover from transient errors.

When to use/Use Cases

Use Retry when errors are temporary (e.g., network hiccups). Use Circuit Breaker when failures are persistent, so the system avoids overloading a struggling dependency.

Example

Calling an API once and it times out: Retry means you try again with a short wait. If it fails multiple times, a Circuit Breaker cuts off calls for a while.

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Why Is It Important

These patterns improve resilience. Retry boosts chances of success on glitches, while Circuit Breaker protects the system from cascading failures and wasted resources.

Interview Tips

Be clear: define both, give a simple analogy, explain when to use each, and mention best practices like exponential backoff with retries and sensible thresholds for circuit breakers.

Trade-offs

Retry improves availability but adds latency and risk of overload. Circuit Breaker increases stability but can temporarily block valid requests.

Pitfalls

Unbounded retries can flood a system. Overly aggressive breakers can block even healthy requests, while too-lenient ones let failures cascade.