默认情况下，Zuul使用不允许设置超时的SEMAPHORE隔离策略。我还没能用这个策略来使用负载平衡。对我有效的是（以你为例）：
背景
我正在使用Spring cloud Brixton.RC2，与Zuul和Eureka一起使用。
我有一个使用@EnableZuulProxy的网关服务和一个具有status方法的book-service。通过配置，我可以通过睡眠定义的时间来模拟status方法的工作。
Zuul路线是简单的
zuul.routes.foos.path=/foos/**
zuul.routes.foos.serviceId=reservation-service
我运行了book-service的两个实例。当我将睡眠时间设置为低于Hystrix超时阈值（1000ms）时，我可以看到两个图书服务实例都收到了请求。这很有效。
问题
我知道，如果Hystrix命令失败，Ribbon应该可以在其他服务器上重试该命令。这将使故障对客户端透明。
我阅读了Ribbon配置，并在Zuul中添加了以下配置：
zuul.routes.reservation-service.retryable=true //not sure which one to try
zuul.routes.foos.retryable=true //not sure which one to try
ribbon.MaxAutoRetries=0 // I don't want to retry on the same host, I also tried with 1 it doesn't work either
ribbon.MaxAutoRetriesNextServer=2
ribbon.OkToRetryOnAllOperations=true
现在我更新了配置，只有一个服务睡眠时间超过1秒，这意味着我有一个健康服务，还有一个不好的。
当我调用网关时，调用会发送到两个实例，其中一半的调用返回500。在网关中，我看到Hystrix超时：
com.netflix.zuul.exception.ZuulException: Forwarding error
[...]
Caused by: com.netflix.hystrix.exception.HystrixRuntimeException: reservation-service timed-out and no fallback available.
[...]
Caused by: java.util.concurrent.TimeoutException: null
为什么Ribbon不在另一个实例上重试调用
我是不是错过了什么
参考文献
- 与此问题相关（未解决）
- 功能区配置
- 根据此提交，Zuul应该支持Ribbon的重试
1） 将Zuul的隔离更改为THREAD:
hystrix:
command:
reservation-service:
execution:
isolation:
strategy: THREAD
thread:
timeoutInMilliseconds: 100000
重要：timeoutInMilliseconds=100000就像不说HystrixTimeout。为什么？因为如果Hystrix超时，就不会有任何负载平衡（我刚刚测试了它的超时InMilliseconds）
然后，将Ribbon的ReadTimeout配置为所需值：
reservation-service:
ribbon:
ReadTimeout: 800
ConnectTimeout: 250
OkToRetryOnAllOperations: true
MaxAutoRetriesNextServer: 2
MaxAutoRetries: 0
在这种情况下，Ribbon中的1秒服务超时后，它将使用500ms服务重试
下面是我在zuul实例中得到的日志：
o.s.web.servlet.DispatcherServlet : DispatcherServlet with name 'dispatcherServlet' processing GET request for [/api/stories]
o.s.web.servlet.DispatcherServlet : Last-Modified value for [/api/stories] is: -1
c.n.zuul.http.HttpServletRequestWrapper : Path = null
c.n.zuul.http.HttpServletRequestWrapper : Transfer-Encoding = null
c.n.zuul.http.HttpServletRequestWrapper : Content-Encoding = null
c.n.zuul.http.HttpServletRequestWrapper : Content-Length header = -1
c.n.loadbalancer.ZoneAwareLoadBalancer : Zone aware logic disabled or there is only one zone
c.n.loadbalancer.LoadBalancerContext : storyteller-api using LB returned Server: localhost:7799 for request /api/stories
---> ATTEMPTING THE SLOW SERVICE
com.netflix.niws.client.http.RestClient : RestClient sending new Request(GET: ) http://localhost:7799/api/stories
c.n.http4.MonitoredConnectionManager : Get connection: {}->http://localhost:7799, timeout = 250
com.netflix.http4.NamedConnectionPool : [{}->http://localhost:7799] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
com.netflix.http4.NamedConnectionPool : No free connections [{}->http://localhost:7799][null]
com.netflix.http4.NamedConnectionPool : Available capacity: 50 out of 50 [{}->http://localhost:7799][null]
com.netflix.http4.NamedConnectionPool : Creating new connection [{}->http://localhost:7799]
com.netflix.http4.NFHttpClient : Attempt 1 to execute request
com.netflix.http4.NFHttpClient : Closing the connection.
c.n.http4.MonitoredConnectionManager : Released connection is not reusable.
com.netflix.http4.NamedConnectionPool : Releasing connection [{}->http://localhost:7799][null]
com.netflix.http4.NamedConnectionPool : Notifying no-one, there are no waiting threads
--- HERE'S RIBBON'S TIMEOUT
c.n.l.reactive.LoadBalancerCommand : Got error com.sun.jersey.api.client.ClientHandlerException: java.net.SocketTimeoutException: Read timed out when executed on server localhost:7799
c.n.loadbalancer.ZoneAwareLoadBalancer : Zone aware logic disabled or there is only one zone
c.n.loadbalancer.LoadBalancerContext : storyteller-api using LB returned Server: localhost:9977 for request /api/stories
---> HERE IT RETRIES
com.netflix.niws.client.http.RestClient : RestClient sending new Request(GET: ) http://localhost:9977/api/stories
c.n.http4.MonitoredConnectionManager : Get connection: {}->http://localhost:9977, timeout = 250
com.netflix.http4.NamedConnectionPool : [{}->http://localhost:9977] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
com.netflix.http4.NamedConnectionPool : Getting free connection [{}->http://localhost:9977][null]
com.netflix.http4.NFHttpClient : Stale connection check
com.netflix.http4.NFHttpClient : Attempt 1 to execute request
com.netflix.http4.NFHttpClient : Connection can be kept alive indefinitely
c.n.http4.MonitoredConnectionManager : Released connection is reusable.
com.netflix.http4.NamedConnectionPool : Releasing connection [{}->http://localhost:9977][null]
com.netflix.http4.NamedConnectionPool : Pooling connection [{}->http://localhost:9977][null]; keep alive indefinitely
com.netflix.http4.NamedConnectionPool : Notifying no-one, there are no waiting threads
o.s.web.servlet.DispatcherServlet : Null ModelAndView returned to DispatcherServlet with name 'dispatcherServlet': assuming HandlerAdapter completed request handling
o.s.web.servlet.DispatcherServlet : Successfully completed request
o.s.web.servlet.DispatcherServlet : DispatcherServlet with name 'dispatcherServlet' processing GET request for [/favicon.ico]
o.s.w.s.handler.SimpleUrlHandlerMapping : Matching patterns for request [/favicon.ico] are [/**/favicon.ico]
o.s.w.s.handler.SimpleUrlHandlerMapping : URI Template variables for request [/favicon.ico] are {}
o.s.w.s.handler.SimpleUrlHandlerMapping : Mapping [/favicon.ico] to HandlerExecutionChain with handler [ResourceHttpRequestHandler [locations=[ServletContext resource [/], class path resource [META-INF/resources/], class path resource [resources/], class path resource [static/], class path resource [public/], class path resource []], resolvers=[org.springframework.web.servlet.resource.PathResourceResolver@a0d875d]]] and 1 interceptor
o.s.web.servlet.DispatcherServlet : Last-Modified value for [/favicon.ico] is: -1
o.s.web.servlet.DispatcherServlet : Null ModelAndView returned to DispatcherServlet with name 'dispatcherServlet': assuming HandlerAdapter completed request handling
o.s.web.servlet.DispatcherServlet : Successfully completed request