eureka客戶端流程圖

eureka客戶端跟server端的機制，基本差不多，用了更多的定時任務和線程，還有保證線程安全的機制，比如： ReentrantLock和CAS

scheduler.schedule(
                    new TimedSupervisorTask(
                            "cacheRefresh",
                            scheduler,
                            cacheRefreshExecutor,
                            registryFetchIntervalSeconds,
                            TimeUnit.SECONDS,
                            expBackOffBound,
                            new CacheRefreshThread()
                    ),
                    registryFetchIntervalSeconds, TimeUnit.SECONDS);