什么是 "Circuit Breaker is open. Execution was short circuited." 以及如何解决这个问题？

Question

我现在做一个简单的负载均衡测试，代码如下：

public static class APIStoreLoadBalancerManager
    {

        private static readonly ConcurrentDictionary<string, ILoadBalancer> _balancers
            = new ConcurrentDictionary<string, ILoadBalancer>();

        private static volatile ManualResetEventSlim _switch = new ManualResetEventSlim(true);

        static APIStoreLoadBalancerManager()
        {
            AutoUpdateUrlMappings();
        }

        public static string ChooseServer(string key)
        {
            string choosenServerHost = null;

            _switch.Wait();

            ILoadBalancer bl = _balancers.GetOrAdd(key, (k) =>
            {
                return new BaseLoadBalancer(ConfigServiceInteraction.GetServiceURLs(k).Split(','), key, null);
            });

            choosenServerHost = bl.ChooseServer(key);

            return choosenServerHost;
        }

        public static void UpdateServerList(string key, IEnumerable<string> serverList)
        {
            ILoadBalancer old = null;
            if (_balancers.TryGetValue(key, out old))
            {
                _balancers[key] = new BaseLoadBalancer(serverList, key, old.Rule);
            }
        }

        private static void UpdateAll()
        {
            IEnumerable<string> list = null;

            foreach (string key in _balancers.Keys)
            {
                try
                {
                    list = ConfigServiceInteraction.GetServiceURLs(key).Split(',');
                    UpdateServerList(key, list);
                }
                catch (System.Exception ex)
                {
                    using (FileStream fs = new FileStream("d:\Error.txt", FileMode.OpenOrCreate, FileAccess.Write, FileShare.Write))
                    {
                        StreamWriter sw = new StreamWriter(fs);
                        sw.WriteLine(ex.StackTrace);
                        sw.WriteLine(ex.Message);
                        sw.WriteLine("================");
                    }
                }
            }
        }


        private static void AutoUpdateUrlMappings()
        {
            Thread thAutoRefresh = new Thread(() =>
            {
                while (true)
                {
                    Thread.Sleep((int)(AppSettings.AutoRefreshMinutes * 60 * 1000));
                    _switch.Reset();
                    UpdateAll();
                    _switch.Set();
                }

            });
            thAutoRefresh.IsBackground = true;
            thAutoRefresh.Start();
        }
    }

现在我们可以像这样简单地调用：

context.RealUrl = APIStoreLoadBalancerManager.ChooseServer("xxx"); //this is a whole global WebApi.

现在我用fiddler手动测试了，结果是：

现在看来是 1 分钟后（自动更新 LOAD BALANCER 的服务 IP 地址...等）。它告诉我：

为什么以及如何修复此类错误？我在 Global 的 Application_Error（写在文件中）中一无所获。

注意：请忽略200和502（它们交替出现，根据我的负载均衡器的算法，这是正确的）。

Answer 1

好吧，这是通过类似 Hystrix 的东西使用的。

什么是 "Circuit Breaker is open. Execution was short circuited." 以及如何解决这个问题？

What is "Circuit Breaker is open. Execution was short circuited." And How to fix this?

c#

asp.net

.net

fiddler