Circuit Breaker Pattern Explained: Stopping Cascading Failures in Microservices

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The Circuit Breaker pattern is a fault-tolerance mechanism used in distributed systems to prevent cascading failures when a dependent service becomes slow or unresponsive. It works by monitoring failure rates and, once a set threshold is crossed, automatically blocking further requests to the failing service and returning immediate errors instead. The pattern operates across three states — Closed (normal), Open (blocking), and Half-Open (testing recovery) — cycling between them based on service health. Common detection strategies include counting consecutive failures, measuring failure rate over a time window, tracking slow call rates, and actively probing service health endpoints. Each approach offers trade-offs between simplicity and accuracy, making the right choice dependent on the specific performance and reliability requirements of the service.

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