hystrix 1.5.13 學習筆記

概述

• 參考
  • https://segmentfault.com/a/1190000005988895
  • http://www.infoq.com/cn/news/2013/01/netflix-hystrix-fault-tolerance
  • http://www.sczyh30.com/posts/Microservice/netflix-hystrix-how-it-works-summary/
  • 用艙壁隔離的方式進行資源隔離,利用熔斷器進行鍊路的保護與恢複

HystrixThreadPool—->資源隔離

• HystrixThreadPoolDefault—->HystrixThreadPool

HystrixCircuitBreaker—->熔斷器

• HystrixCircuitBreakerImpl—->HystrixCircuitBreaker
  • com.netflix.hystrix.HystrixCircuitBreaker.HystrixCircuitBreakerImpl#attemptExecution—->指令根據此方法判斷是否應該執行
    • 基于circuitBreakerForceOpen(false)/default_circuitBreakerForceClosed(false)
    • circuitOpened—->熔斷打開時間(-1)
    • isAfterSleepWindow—->是否是在熔斷的休眠時間後,基于currentTime > circuitOpenTime + sleepWindowTime(circuitBreakerSleepWindowInMilliseconds—-5000ms)
    • 置熔斷狀态為半開狀态status.compareAndSet(Status.OPEN, Status.HALF_OPEN)
  • com.netflix.hystrix.HystrixCircuitBreaker.HystrixCircuitBreakerImpl#subscribeToStream
    • 當達到設定的閥值時,status.compareAndSet(Status.CLOSED, Status.OPEN)
• NoOpCircuitBreaker—->HystrixCircuitBreaker—–>關閉熔斷支援
• 熔斷器三種狀态—->CLOSED, OPEN, HALF_OPEN

HystrixCommand—->指令模式

• HystrixCommand—->AbstractCommand
• terminateCommandCleanup—->完成清理動作
• unsubscribeCommandCleanup—->完成從status.compareAndSet(Status.HALF_OPEN, Status.OPEN)的轉化
• com.netflix.hystrix.AbstractCommand#applyHystrixSemantics—->核心流程方法
  • com.netflix.hystrix.AbstractCommand#executeCommandAndObserve
  • com.netflix.hystrix.AbstractCommand#executeCommandWithSpecifiedIsolation
  • 正常回調
    • com.netflix.hystrix.AbstractCommand#getUserExecutionObservable—->調用HystrixCommand的方法,進行回調業務系統
    • com.netflix.hystrix.HystrixCommand#getExecutionObservable—->回調使用者定義的業務run方法
  • 異常回調
    • com.netflix.hystrix.AbstractCommand#handleShortCircuitViaFallback
    • com.netflix.hystrix.AbstractCommand#getFallbackOrThrowException
    • com.netflix.hystrix.HystrixCommand#getFallbackObservable—->回調使用者定義的業務異常getFallback方法

HystrixKeyDefault—->HystrixKey—->key支援(String name)

• HystrixThreadPoolKey—->利用intern存放以name為key,HystrixThreadPoolKeyDefault為值的Map
• HystrixCommandKey—->利用intern存放以name為key,HystrixCommandKeyDefault為值的Map
• HystrixCommandGroupKey—->利用intern存放以name為key,HystrixCommandGroupDefault為值的Map
• HystrixCollapserKey—->利用intern存放以name為key,HystrixCollapserKeyDefault為值的Map

屬性支援—->例如指令屬性、線程池屬性

• HystrixThreadPoolProperties
• HystrixCommandProperties
• HystrixCollapserProperties

HystrixMetrics—->例如名額資訊

• HystrixThreadPoolMetrics—->HystrixMetrics—->名額資訊
• HystrixCommandMetrics—->HystrixMetrics
• HystrixCollapserMetrics—->HystrixMetrics

測試

• com.netflix.hystrix.examples.demo.HystrixCommandDemo