hystrix(4) properties配置

这一节我们来讲hystrix的properties配置体系，properties配置也是各个功能模块的基础功能。hystrix将配置分成三个部分：

　　1.HystrixCommandProperties用于HystrixCommand配置，一个HystrixCommandKey对应一个HystrixCommandProperties实例。

　　2.HystrixThreadPoolProperties用于HystrixThreadPool配置，一个HystrixThreadPoolKey对应一个HystrixThreadPoolProperties实例。

　　3.HystrixCollapserProperties用于HystrixCollapserCommand配置，一个HystrixCollapserKey对应一个HystrixCollapserProperties实例。

类别	配置项	默认值	说明
HystrixCommandProperties	hystrix.threadpool.[commandkey].circuitBreaker.enabled	true
	hystrix.threadpool.[commandkey].circuitBreaker.requestVolumeThreshold	20
	hystrix.threadpool.[commandkey].circuitBreaker.sleepWindowInMilliseconds	5000
	hystrix.threadpool.[commandkey].circuitBreaker.errorThresholdPercentage	50
	hystrix.threadpool.[commandkey].circuitBreaker.forceOpen	false
	hystrix.threadpool.[commandkey].circuitBreaker.forceClosed	false
	hystrix.threadpool.[commandkey].execution.isolation.strategy	Thread
	hystrix.threadpool.[commandkey].execution.isolation.thread.timeoutInMilliseconds	1000
	hystrix.threadpool.[commandkey].execution.timeout.enabled	true
	hystrix.threadpool.[commandkey].execution.isolation.thread.interruptOnTimeout	true
	hystrix.threadpool.[commandkey].execution.isolation.thread.interruptOnFutureCancel	false
	hystrix.threadpool.[commandkey].execution.isolation.semaphore.maxConcurrentRequests	10
	hystrix.threadpool.[commandkey].fallback.isolation.semaphore.maxConcurrentRequests	10
	hystrix.threadpool.[commandkey].fallback.enabled	true
	hystrix.threadpool.[commandkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.threadpool.[commandkey].metrics.rollingStats.numBuckets	10
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.enabled	true
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.timeInMilliseconds	60000
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.numBuckets	6
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.bucketSize	100
	hystrix.threadpool.[commandkey].metrics.healthSnapshot.intervalInMilliseconds	500
	hystrix.threadpool.[commandkey].requestCache.enabled	true
	hystrix.threadpool.[commandkey].requestLog.enabled	true
	hystrix.threadpool.[commandkey].threadPoolKeyOverride
HystrixThreadPoolProperties	hystrix.threadpool.[threadPoolkey].coreSize	10
	hystrix.threadpool.[threadPoolkey].allowMaximumSizeToDivergeFromCoreSize	false
	hystrix.threadpool.[threadPoolkey].maximumSize	10
	hystrix.threadpool.[threadPoolkey].keepAliveTimeMinutes	1
	hystrix.threadpool.[threadPoolkey].maxQueueSize	-1
	hystrix.threadpool.[threadPoolkey].queueSizeRejectionThreshold	5
	hystrix.threadpool.[threadPoolkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.threadpool.[threadPoolkey].metrics.rollingStats.numBuckets	10
HystrixCollapserProperties	hystrix.collapser.[collapserCommandkey].maxRequestsInBatch	Integer.MAX_VALUE
	hystrix.collapser.[collapserCommandkey].timerDelayInMilliseconds	10
	hystrix.collapser.[collapserCommandkey].requestCache.enabled	true
	hystrix.collapser.[collapserCommandkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.collapser.[collapserCommandkey].metrics.rollingStats.numBuckets	10
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.enabled	true
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.timeInMilliseconds	60000
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.numBuckets	6
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.bucketSize	100

　　内部每个属性由一个ChainHystrixProperty表示，ChainHystrixProperty是一个串联的HystrixDynamicProperty，持续获取串中的属性值，直到获得不为null值为止。ChainHystrixProperty串联的HystrixDynamicProperty默认通过插件获取的HystrixDynamicProperties获取（最后我们会讲到插件）。

　　HystrixDynamicProperty表示动态配置数据，如果配置源发送变化，通过该对象获取配置也会相应变化。hystrix中有种实现类：

　　　　1.通过archaius实现获取配置项，通过HystrixDynamicPropertiesArchaius创建该类HystrixDynamicProperty。

　　　　2.通过system实现获取配置项，通过HystrixDynamicPropertiesSystemProperties创建该类HystrixDynamicProperty。