淺析Spring Boot單體應用熔斷技術的使用
壹、入圍方案
Sentinel
- github地址:https://sentinelguard.io/zh-cn/docs/introduction.html
- 阿里出品,Spring Cloud Alibaba限流組件,目前持續(xù)更新中
- 自帶Dashboard,可以查看接口Qps等,并且可以動態(tài)修改各種規(guī)則
- 流量控制,直接限流、冷啟動、排隊
- 熔斷降級,限制并發(fā)限制數(shù)和相應時間
- 系統(tǒng)負載保護,提供系統(tǒng)級別防護,限制總體CPU等
- 主要核心:資源,規(guī)則(流量控制規(guī)則、熔斷降級規(guī)則、系統(tǒng)保護規(guī)則、來源訪問控制規(guī)則 和 熱點參數(shù)規(guī)則。),和指標
- 文檔非常清晰和詳細,中文
- 支持動態(tài)規(guī)則(推模式和拉模式)
Hystrix
- github地址:https://github.com/Netflix/Hystrix/wiki
- Netflix出品,Spring Cloud Netflix限流組件,已經停止新特性開發(fā),只進行bug修復,最近更新為2018年,功能穩(wěn)定
- 有簡單的dashboard頁面
- 以隔離和熔斷為主的容錯機制,超時或被熔斷的調用將會快速失敗,并可以提供 fallback 機制的初代熔斷框架,異常統(tǒng)計基于滑動窗口
resilience4j
- github地址:https://resilience4j.readme.io/docs
- 是一款輕量、簡單,并且文檔非常清晰、豐富的熔斷工具。是Hystrix替代品,實現(xiàn)思路和Hystrix一致,目前持續(xù)更新中
- 需要自己對micrometer、prometheus以及Dropwizard metrics進行整合
- CircuitBreaker 熔斷
- Bulkhead 隔離
- RateLimiter QPS限制
- Retry 重試
- TimeLimiter 超時限制
- Cache 緩存
自己實現(xiàn)(基于Guava)
- 基于Guava的令牌桶,可以輕松實現(xiàn)對QPS進行限流
貳、技術對比
叁、應用改造
3.1、sentinel
3.1.1、引入依賴
<dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId> <version>2.0.3.RELEASE</version> </dependency>
3.1.2、改造接口或者service層
@SentinelResource(value = "allInfos",fallback = "errorReturn")
@Target({ElementType.METHOD, ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Inherited public @interface SentinelResource { //資源名稱 String value() default ""; //流量方向 EntryType entryType() default EntryType.OUT; //資源類型 int resourceType() default 0; //異常處理方法 String blockHandler() default ""; //異常處理類 Class<?>[] blockHandlerClass() default {}; //熔斷方法 String fallback() default ""; //默認熔斷方法 String defaultFallback() default ""; //熔斷類 Class<?>[] fallbackClass() default {}; //統(tǒng)計異常 Class<? extends Throwable>[] exceptionsToTrace() default {Throwable.class}; //忽略異常 Class<? extends Throwable>[] exceptionsToIgnore() default {}; }
@RequestMapping("/get") @ResponseBody @SentinelResource(value = "allInfos",fallback = "errorReturn") public JsonResult allInfos(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num){ try { if (num % 2 == 0) { log.info("num % 2 == 0"); throw new BaseException("something bad with 2", 400); } return JsonResult.ok(); } catch (ProgramException e) { log.info("error"); return JsonResult.error("error"); } }
3.1.3、針對接口配置熔斷方法或者限流方法
默認過濾攔截所有Controller接口
/** * 限流,參數(shù)需要和方法保持一致 * @param request * @param response * @param num * @return * @throws BlockException */ public JsonResult errorReturn(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num) throws BlockException { return JsonResult.error("error 限流" + num ); } /** * 熔斷,參數(shù)需要和方法保持一直,并且需要添加BlockException異常 * @param request * @param response * @param num * @param b * @return * @throws BlockException */ public JsonResult errorReturn(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num,BlockException b) throws BlockException { return JsonResult.error("error 熔斷" + num ); }
注意也可以不配置限流或者熔斷方法。通過全局異常去捕獲UndeclaredThrowableException或者BlockException避免大量的開發(fā)量
3.1.4、接入dashboard
spring: cloud: sentinel: transport: port: 8719 dashboard: localhost:8080
3.1.5、規(guī)則持久化和動態(tài)更新
接入配置中心如:zookeeper等等,并對規(guī)則采用推模式
3.2、hystrix
3.2.1、引入依賴
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId> <version>2.0.4.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> <version>2.0.4.RELEASE</version> </dependency>
3.2.2、改造接口
@HystrixCommand(fallbackMethod = "timeOutError")
@Target({ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) @Inherited @Documented public @interface HystrixCommand { String groupKey() default ""; String commandKey() default ""; String threadPoolKey() default ""; String fallbackMethod() default ""; HystrixProperty[] commandProperties() default {}; HystrixProperty[] threadPoolProperties() default {}; Class<? extends Throwable>[] ignoreExceptions() default {}; ObservableExecutionMode observableExecutionMode() default ObservableExecutionMode.EAGER; HystrixException[] raiseHystrixExceptions() default {}; String defaultFallback() default ""; }
@RequestMapping("/get") @ResponseBody @HystrixCommand(fallbackMethod = "fallbackMethod") public JsonResult allInfos(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num){ try { if (num % 3 == 0) { log.info("num % 3 == 0"); throw new BaseException("something bad whitch 3", 400); } return JsonResult.ok(); } catch (ProgramException | InterruptedException exception) { log.info("error"); return JsonResult.error("error"); } }
3.2.3、針對接口配置熔斷方法
/** * 該方法是熔斷回調方法,參數(shù)需要和接口保持一致 * @param request * @param response * @param num * @return */ public JsonResult fallbackMethod(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num) { response.setStatus(500); log.info("發(fā)生了熔斷??!"); return JsonResult.error("熔斷"); }
3.2.4、配置默認策略
hystrix: command: default: execution: isolation: strategy: THREAD thread: # 線程超時15秒,調用Fallback方法 timeoutInMilliseconds: 15000 metrics: rollingStats: timeInMilliseconds: 15000 circuitBreaker: # 10秒內出現(xiàn)3個以上請求(已臨近閥值),并且出錯率在50%以上,開啟斷路器.斷開服務,調用Fallback方法 requestVolumeThreshold: 3 sleepWindowInMilliseconds: 10000
3.2.5、接入監(jiān)控
曲線:用來記錄2分鐘內流量的相對變化,我們可以通過它來觀察到流量的上升和下降趨勢。
集群監(jiān)控需要用到注冊中心
3.3、resilience4j
3.3.1、引入依賴
dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-spring-boot2</artifactId> <version>1.6.1</version> </dependency> <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-bulkhead</artifactId> <version>1.6.1</version> </dependency> <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-ratelimiter</artifactId> <version>1.6.1</version> </dependency> <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-timelimiter</artifactId> <version>1.6.1</version> </dependency>
可以按需要引入:bulkhead,ratelimiter,timelimiter等
3.3.2、改造接口
@RequestMapping("/get") @ResponseBody //@TimeLimiter(name = "BulkheadA",fallbackMethod = "fallbackMethod") @CircuitBreaker(name = "BulkheadA",fallbackMethod = "fallbackMethod") @Bulkhead(name = "BulkheadA",fallbackMethod = "fallbackMethod") public JsonResult allInfos(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num){ log.info("param----->" + num); try { //Thread.sleep(num); if (num % 2 == 0) { log.info("num % 2 == 0"); throw new BaseException("something bad with 2", 400); } if (num % 3 == 0) { log.info("num % 3 == 0"); throw new BaseException("something bad whitch 3", 400); } if (num % 5 == 0) { log.info("num % 5 == 0"); throw new ProgramException("something bad whitch 5", 400); } if (num % 7 == 0) { log.info("num % 7 == 0"); int res = 1 / 0; } return JsonResult.ok(); } catch (BufferUnderflowException e) { log.info("error"); return JsonResult.error("error"); } }
3.3.3、針對接口配置熔斷方法
/** * 需要參數(shù)一致,并且加上相應異常 * @param request * @param response * @param num * @param exception * @return */ public JsonResult fallbackMethod(HttpServletRequest request, HttpServletResponse response, @RequestParam Integer num, BulkheadFullException exception) { return JsonResult.error("error 熔斷" + num ); }
3.3.4、配置規(guī)則
resilience4j.circuitbreaker: instances: backendA: registerHealthIndicator: true slidingWindowSize: 100 backendB: registerHealthIndicator: true slidingWindowSize: 10 permittedNumberOfCallsInHalfOpenState: 3 slidingWindowType: TIME_BASED minimumNumberOfCalls: 20 waitDurationInOpenState: 50s failureRateThreshold: 50 eventConsumerBufferSize: 10 recordFailurePredicate: io.github.robwin.exception.RecordFailurePredicate resilience4j.retry: instances: backendA: maxRetryAttempts: 3 waitDuration: 10s enableExponentialBackoff: true exponentialBackoffMultiplier: 2 retryExceptions: - org.springframework.web.client.HttpServerErrorException - java.io.IOException ignoreExceptions: - io.github.robwin.exception.BusinessException backendB: maxRetryAttempts: 3 waitDuration: 10s retryExceptions: - org.springframework.web.client.HttpServerErrorException - java.io.IOException ignoreExceptions: - io.github.robwin.exception.BusinessException resilience4j.bulkhead: instances: backendA: maxConcurrentCalls: 10 backendB: maxWaitDuration: 10ms maxConcurrentCalls: 20 resilience4j.thread-pool-bulkhead: instances: backendC: maxThreadPoolSize: 1 coreThreadPoolSize: 1 queueCapacity: 1 resilience4j.ratelimiter: instances: backendA: limitForPeriod: 10 limitRefreshPeriod: 1s timeoutDuration: 0 registerHealthIndicator: true eventConsumerBufferSize: 100 backendB: limitForPeriod: 6 limitRefreshPeriod: 500ms timeoutDuration: 3s resilience4j.timelimiter: instances: backendA: timeoutDuration: 2s cancelRunningFuture: true backendB: timeoutDuration: 1s cancelRunningFuture: false
配置的規(guī)則可以被代碼覆蓋
3.3.5、配置監(jiān)控
如grafana等
肆、關注點
- 是否需要過濾部分異常
- 是否需要全局默認規(guī)則
- 可能需要引入其他中間件
- k8s流量控制
- 規(guī)則存儲和動態(tài)修改
- 接入改造代價
【后面的話】
個人建議的話,比較推薦sentinel,它提供了很多接口便于開發(fā)者自己拓展,同時我覺得他的規(guī)則動態(tài)更新也比較方便。最后是相關示例代碼:單體應用示例代碼
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