Resiliency in Microservices: A Guide to Circuit Breaker Pattern

The Circuit Breaker pattern in microservices enhances resilience by monitoring service calls to dependencies. When failures, errors, or timeouts exceed a defined threshold, the circuit “opens,” halting further requests to the failing service. During this downtime, fallback mechanisms like pre-cached data or alternative logic handle requests, ensuring the system remains operational and avoids overloading the failing service. After a cooldown period, the circuit enters a “half-open” state to test recovery, sending limited requests to check if the service is stable. If successful, the circuit “closes,” and normal operations resume. This pattern prevents cascading failures, reduces latency during outages, and ensures better fault tolerance, particularly in high-traffic systems with critical external dependencies.

For example, in a payment system, if a fraud-check API fails repeatedly, the circuit breaker opens, skipping further API calls and returning cached risk scores. This ensures transaction flow continues while the API recovers, avoiding disruptions. This pattern improves fault tolerance and system resilience during partial outages or high traffic.

Scenario and Problem Explanation:

In a distributed environment, applications often make calls to remote resources or…