Add ThreadPool and CPU summary to connection related errors.

StackExchange.Redis/StackExchange/Redis/ConnectionMultiplexer.cs

@@ -2071,6 +2071,14 @@ internal T ExecuteSyncImpl<T>(Message message, ResultProcessor<T> processor, Ser
         }
 
 #if !CORE_CLR
+        internal static string GetThreadPoolAndCPUSummary()
+        {
+            string iocp, worker;
+            GetThreadPoolStats(out iocp, out worker);
+            var cpu = GetSystemCpuPercent();
+            return $"IOCP: {iocp}, WORKER: {worker}, Local-CPU: {cpu}";
+        }
+
         private static string GetSystemCpuPercent()
         {
             float systemCPU;

StackExchange.Redis/StackExchange/Redis/ExceptionFactory.cs

@@ -86,6 +86,13 @@ internal static Exception NoConnectionAvailable(bool includeDetail, RedisCommand
                 serverSnapshot = new ServerEndPoint[] { server };
             }
             string exceptionmessage = "No connection is available to service this operation: " + s ;
+
+#if !CORE_CLR
+            if (includeDetail)
+            {
+                exceptionmessage += ". " + ConnectionMultiplexer.GetThreadPoolAndCPUSummary();
+            }
+#endif
             var ex = new RedisConnectionException(ConnectionFailureType.UnableToResolvePhysicalConnection, exceptionmessage, GetServerSnapshotInnerExceptions(serverSnapshot));
             if (includeDetail)
             {

StackExchange.Redis/StackExchange/Redis/ResultProcessor.cs

@@ -164,7 +164,10 @@ public virtual bool SetResult(PhysicalConnection connection, Message message, Ra
                             }
                             else
                             {
-                                err = string.Format("Endpoint {0} serving hashslot {1} is not reachable at this point of time. Please check connectTimeout value. If it is low, try increasing it to give the ConnectionMultiplexer a chance to recover from the network disconnect.", endpoint, hashSlot);
+                                err = string.Format("Endpoint {0} serving hashslot {1} is not reachable at this point of time. Please check connectTimeout value. If it is low, try increasing it to give the ConnectionMultiplexer a chance to recover from the network disconnect.  ", endpoint, hashSlot);
+#if !CORE_CLR
+                                err += ConnectionMultiplexer.GetThreadPoolAndCPUSummary();
+#endif
                             }
                         }
                     }