Resilience4j 断路器不工作

Question

我遇到了使用 Spring Cloud Resilience4j 实现断路器的问题。

按照一些教程，我尝试在项目中添加必要的依赖项。 另外，尝试添加配置，但仍然没有打开电路，也没有调用回退方法。

对于用例，我正在从我的服务调用一个外部 API，如果该外部 API 关闭，那么在几次调用之后，我需要启用断路器。

请从不同的文件中找到代码片段。

我是断路器模式的新手。任何帮助将不胜感激。

pom.xml

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
<parent>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-parent</artifactId>
   <version>2.5.5</version>
   <relativePath/> <!-- lookup parent from repository -->
</parent>
    <properties>
    <java.version>11</java.version>
    <spring-cloud.version>2020.0.4</spring-cloud.version>
    </properties>
    <dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-circuitbreaker-resilience4j</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>
<dependencies>
</project>

应用程序属性

resilience4j.circuitbreaker.instances.test-api.register-health-indicator=true
resilience4j.circuitbreaker.instances.test-api.minimum-number-of-calls=4
resilience4j.circuitbreaker.instances.test-api.failure-rate-threshold=50
resilience4j.circuitbreaker.instances.test-api.permitted-number-of-calls-in-half-open-state=3
resilience4j.circuitbreaker.instances.test-api.wait-duration-in-open-state=30s
resilience4j.circuitbreaker.instances.test-api.automatic-transition-from-open-to-half-open-enabled=true
resilience4j.circuitbreaker.instances.test-api.record-exceptions=com.testapi.exception.ServiceUnavailableError

服务类代码片段

@CircuitBreaker(name = "test-api", fallbackMethod = "storeResponseFallback")
    public TestResponse storeResponse(String apiURL, HttpEntity<String> entityrequest) {

        TestResponse testResponse = new TestResponse();
        Optional<ResponseEntity<TestResponse>> response = Optional.empty();
        Future<ResponseEntity<TestResponse>> responseFuture;

        ExecutorService executor = Executors.newFixedThreadPool(10);

        log.debug("Calling Extrenal API, Request Body: {}", entityrequest.toString());

        try {
            //Service call returns a future
            responseFuture = executor.submit(() -> restTemplate.postForEntity(apiURL, entityrequest, TestResponse.class));
            response = Optional.ofNullable(responseFuture.get());
            log.info("Got response from external API");


            if ((response.isPresent()) && (response.get().hasBody())) {
                testResponse = response.get().getBody();
            }

        } catch (Exception exception) {
            log.error("External api call got failed with an error");
            Thread.currentThread().interrupt();            
            throw new ServiceUnavailableError();
        }


        return testResponse;

    }
    
    
    public TestResponse storeResponseFallback(ServiceUnavailableError ex) {
        log.error("Executing Fallback Method For General exceptions");
        throw new ServiceUnavailableError();
    }

ServiceUnavailableError Java 文件

@Data
@AllArgsConstructor
@NoArgsConstructor
public class ServiceUnavailableError extends RuntimeException{
    private static final long serialVersionUID = 2382122402994502766L;

    private String message;

}

Answer 1

您的回退方法的签名是错误的。它应该包含实际方法的所有参数（在您的情况下，storeResponseFallback 是回退方法，storeResponse 是实际方法）以及异常。请确保删除 try catch 块。您不想自己处理异常，而是应该让断路器为您处理它。 请查看以下来自给定链接的代码 https://resilience4j.readme.io/docs/getting-started-3

@CircuitBreaker(name = BACKEND, fallbackMethod = "fallback")
public Mono<String> method(String param1) {
    return Mono.error(new NumberFormatException());
}

private Mono<String> fallback(String param1, IllegalArgumentException e) {
    return Mono.just("test");
}

尝试使用以下 yaml 文件 我将以下配置与您现有的代码一起使用，我使用 yaml 而不是属性文件。这似乎保持在打开状态并仅调用回退方法。

resilience4j.circuitbreaker:
  configs:
    default:
      slidingWindowSize: 4
      permittedNumberOfCallsInHalfOpenState: 10
      waitDurationInOpenState: 10000
      failureRateThreshold: 60
      eventConsumerBufferSize: 10
      registerHealthIndicator: true
    someShared:
      slidingWindowSize: 3
      permittedNumberOfCallsInHalfOpenState: 10
  instances:
    test-api:
      baseConfig: default
      waitDurationInOpenState: 500000
    backendB:
      baseConfig: someShared

这是更新后的回退方法

public TestResponse storeResponseFallback(String apiURL, String entityrequest, java.lang.Throwable t) {
        log.error("Executing Fallback Method For General exceptions "+t.getMessage());
        return new TestResponse("Frm Fallback");// Making sure to send a blank response
    }