In microservices, every network call can fail. A slow dependency can exhaust your thread pool, cascading into a full outage. Resilience4j provides the patterns to handle these failures gracefully — without hiding them. Setup <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-spring-boot3</artifactId> <version>2.2.0</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> Circuit Breaker A circuit breaker wraps a remote call. When failures exceed a threshold, the circuit “opens” and calls fail immediately (without waiting for a timeout) — protecting your thread pool and giving the failing service time to recover.