Pattern 19 / RESILIENCE

Circuit Breaker

Use this when stopping a failing dependency from exhausting callers.

Pressure: Stopping a failing dependency from exhausting callers
Mechanism: Track failures, open the circuit after a threshold, return fallback, then probe for recovery
Toll: Fallbacks may be degraded and thresholds must fit real failure modes

Diagram for Circuit Breaker — Architecture plate19

Executive brief

Circuit Breaker fits when stopping a failing dependency from exhausting callers. Mechanism: track failures, open the circuit after a threshold, return fallback, then probe for recovery. Use it for any service call to a dependency whose failure should be isolated. The toll: fallbacks may be degraded and thresholds must fit real failure modes.

Use when

Any service call to a dependency whose failure should be isolated.

Example

Recommendation service down → show trending products.

Review framing

Describe the pressure first, then the mechanism, then the cost. That keeps the design grounded.

Same pressure family

Reliability Patterns

20Retry with Exponential Backoff 21Bulkhead 22Timeout 23Idempotency 24Dead Letter Queue (DLQ)25Graceful Degradation