Hystrix 服务熔断-配置及参数设置

DeathAndLife

6343人浏览 · 2020-06-24 10:39:41

DeathAndLife · 2020-06-24 10:39:41 发布

简介

“断路器” 本身是一种开关装置，当某个服务单元发生故障之后，通过断路器的故障监控（类似保险熔断），向调用方法返回一个符合预期的，可处理的被选响应（FallBack）, 而不是长时间的等待或者抛出调用方法无法处理的异常，这样就保证了服务调用方的线程不会长时间，不必要地占用，从而避免了故障在分布式系统中的蔓延，从而导致雪崩效应。

POM(版本根据自己使用的SpringBoot版本自定)

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>

YAML(用的Consul注册中心)

server:
  port: 8001
spring:
  application:
    name: cloud-provider-hystrix-payment8001
  cloud:
    consul:
      discovery:
        prefer-ip-address: true
        service-name: ${spring.application.name}
        instance-id: payment8001
      port: 8500
      host: localhost

启动类

@EnableCircuitBreaker 启用断路器（熔断支持）

import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@EnableCircuitBreaker
public class HystrixProviderMain8001 {

    public static void main(String[] args) {
        SpringApplication.run(HystrixProviderMain8001.class,args);
    }

}

Service

注意：如果再调用的方法上有形参，那么fallback方法也同样需要形参；不然会报 `找不到fallback方法异常`

设置服务熔断的核心配置：

启用断路器 @HystrixProperty(name = "circuitBreaker.enabled", value = "true")
设置请求次数 @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10")
设置时间窗口期 @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000")
设置失败率 @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "60")

如上设置的值，如果在10秒内，失败率达到请求次数（10）的百分之60，也就是6次就会打开断路器；否则断路器依然关闭

当断路器开启时，所有的请求都不会转发，而是直接调用fallback方法；在一段时间后（默认5秒），断路器处于半开状态，尝试将请求转发，如果得到正确的响应。则将断路器关闭，恢复正常调用；否则断路器状态再次打开，重新计时后再进入半开状态

import cn.hutool.core.util.IdUtil;
import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

@Component
public class PaymentService {

    @HystrixCommand(fallbackMethod = "breakFallback", commandProperties = {
            // 开启断路器
            @HystrixProperty(name = "circuitBreaker.enabled", value = "true"),
            // 请求次数
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),
            // 时间窗口期
            @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"),
            // 失败率
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "60")
    })
    public String breakTest(Integer id) {
        if (id < 0) {
            throw new RuntimeException("ID 不能为负数");
        }
        return "正常访问： " + IdUtil.simpleUUID();
    }

    public String breakFallback(Integer id) {
        return Thread.currentThread().getName() + "ID 不能为负数 熔断服务降级FallBack!" + id;
    }

}

更多的@HystrixCommand属性设置查看HystrixCommandProperties类

protected HystrixCommandProperties(HystrixCommandKey key, HystrixCommandProperties.Setter builder, String propertyPrefix) {
        this.key = key;
        this.circuitBreakerEnabled = getProperty(propertyPrefix, key, "circuitBreaker.enabled", builder.getCircuitBreakerEnabled(), default_circuitBreakerEnabled);
        this.circuitBreakerRequestVolumeThreshold = getProperty(propertyPrefix, key, "circuitBreaker.requestVolumeThreshold", builder.getCircuitBreakerRequestVolumeThreshold(), default_circuitBreakerRequestVolumeThreshold);
        this.circuitBreakerSleepWindowInMilliseconds = getProperty(propertyPrefix, key, "circuitBreaker.sleepWindowInMilliseconds", builder.getCircuitBreakerSleepWindowInMilliseconds(), default_circuitBreakerSleepWindowInMilliseconds);
        this.circuitBreakerErrorThresholdPercentage = getProperty(propertyPrefix, key, "circuitBreaker.errorThresholdPercentage", builder.getCircuitBreakerErrorThresholdPercentage(), default_circuitBreakerErrorThresholdPercentage);
        this.circuitBreakerForceOpen = getProperty(propertyPrefix, key, "circuitBreaker.forceOpen", builder.getCircuitBreakerForceOpen(), default_circuitBreakerForceOpen);
        this.circuitBreakerForceClosed = getProperty(propertyPrefix, key, "circuitBreaker.forceClosed", builder.getCircuitBreakerForceClosed(), default_circuitBreakerForceClosed);
        this.executionIsolationStrategy = getProperty(propertyPrefix, key, "execution.isolation.strategy", builder.getExecutionIsolationStrategy(), default_executionIsolationStrategy);
        this.executionTimeoutInMilliseconds = getProperty(propertyPrefix, key, "execution.isolation.thread.timeoutInMilliseconds", builder.getExecutionIsolationThreadTimeoutInMilliseconds(), default_executionTimeoutInMilliseconds);
        this.executionTimeoutEnabled = getProperty(propertyPrefix, key, "execution.timeout.enabled", builder.getExecutionTimeoutEnabled(), default_executionTimeoutEnabled);
        this.executionIsolationThreadInterruptOnTimeout = getProperty(propertyPrefix, key, "execution.isolation.thread.interruptOnTimeout", builder.getExecutionIsolationThreadInterruptOnTimeout(), default_executionIsolationThreadInterruptOnTimeout);
        this.executionIsolationThreadInterruptOnFutureCancel = getProperty(propertyPrefix, key, "execution.isolation.thread.interruptOnFutureCancel", builder.getExecutionIsolationThreadInterruptOnFutureCancel(), default_executionIsolationThreadInterruptOnFutureCancel);
        this.executionIsolationSemaphoreMaxConcurrentRequests = getProperty(propertyPrefix, key, "execution.isolation.semaphore.maxConcurrentRequests", builder.getExecutionIsolationSemaphoreMaxConcurrentRequests(), default_executionIsolationSemaphoreMaxConcurrentRequests);
        this.fallbackIsolationSemaphoreMaxConcurrentRequests = getProperty(propertyPrefix, key, "fallback.isolation.semaphore.maxConcurrentRequests", builder.getFallbackIsolationSemaphoreMaxConcurrentRequests(), default_fallbackIsolationSemaphoreMaxConcurrentRequests);
        this.fallbackEnabled = getProperty(propertyPrefix, key, "fallback.enabled", builder.getFallbackEnabled(), default_fallbackEnabled);
        this.metricsRollingStatisticalWindowInMilliseconds = getProperty(propertyPrefix, key, "metrics.rollingStats.timeInMilliseconds", builder.getMetricsRollingStatisticalWindowInMilliseconds(), default_metricsRollingStatisticalWindow);
        this.metricsRollingStatisticalWindowBuckets = getProperty(propertyPrefix, key, "metrics.rollingStats.numBuckets", builder.getMetricsRollingStatisticalWindowBuckets(), default_metricsRollingStatisticalWindowBuckets);
        this.metricsRollingPercentileEnabled = getProperty(propertyPrefix, key, "metrics.rollingPercentile.enabled", builder.getMetricsRollingPercentileEnabled(), default_metricsRollingPercentileEnabled);
        this.metricsRollingPercentileWindowInMilliseconds = getProperty(propertyPrefix, key, "metrics.rollingPercentile.timeInMilliseconds", builder.getMetricsRollingPercentileWindowInMilliseconds(), default_metricsRollingPercentileWindow);
        this.metricsRollingPercentileWindowBuckets = getProperty(propertyPrefix, key, "metrics.rollingPercentile.numBuckets", builder.getMetricsRollingPercentileWindowBuckets(), default_metricsRollingPercentileWindowBuckets);
        this.metricsRollingPercentileBucketSize = getProperty(propertyPrefix, key, "metrics.rollingPercentile.bucketSize", builder.getMetricsRollingPercentileBucketSize(), default_metricsRollingPercentileBucketSize);
        this.metricsHealthSnapshotIntervalInMilliseconds = getProperty(propertyPrefix, key, "metrics.healthSnapshot.intervalInMilliseconds", builder.getMetricsHealthSnapshotIntervalInMilliseconds(), default_metricsHealthSnapshotIntervalInMilliseconds);
        this.requestCacheEnabled = getProperty(propertyPrefix, key, "requestCache.enabled", builder.getRequestCacheEnabled(), default_requestCacheEnabled);
        this.requestLogEnabled = getProperty(propertyPrefix, key, "requestLog.enabled", builder.getRequestLogEnabled(), default_requestLogEnabled);
        this.executionIsolationThreadPoolKeyOverride = HystrixPropertiesChainedProperty.forString().add(propertyPrefix + ".command." + key.name() + ".threadPoolKeyOverride", (Object)null).build();
    }