SignalR hub scaling issue

Question

We have a SignalR hub called StatusUpdateHub. This hub is updated by a .NET client called HubClient. This client will be (in production), called several thousand times per second by several users for different transactions. Here is the client code:

public static class HubClient { private static readonly string statusUpdateUrl = ConfigurationManager.AppSettings["StatusUpdateUrl"]; private static readonly HubConnection connection = new HubConnection(statusUpdateUrl); private static readonly IHubProxy hub = connection.CreateProxy("StatusUpdateHub"); internal static void UpdateBrowser(long transactionId) { connection.Start().ContinueWith(task => hub.Invoke("UpdateTransactionStatus", transactionId)).ContinueWith(task => { if (task.IsFaulted && task.Exception != null) { // log error } }); } } 

When this code is called with 100 concurrent users, it works fine, but when we increase the number of concurrent users to 250, we see the following error:

Unexpected error in UpdateBrowser: System.InvalidOperationException: Connection failed. in SignalR.Client.Connection.SignalR.Client.IConnection.Send [T] (Data String) in SignalR.Client.Hubs.HubProxy.Invoke [T] (String method, Object [] args) in SignalR.Client.Hubs. HubProxy.Invoke (String method, Object [] args) with Application.Services.HubClient <. > C_DisplayClass2.b_0 (Task task1) in c: \ Build \ Work \ Application \ Services \ HubClient.cs: line 20
in System.Threading.Tasks.Task`1.InvokeFuture (Object futureAsObj)
in System.Threading.Tasks.Task.Execute ()

Let us know how to make the code more scalable?

Answer 1

If this method is called 1000 times per second, you should not call connection.Start() every time.

Open the connection only once, and then just call the methods on it.

Edit , I mean that at least make your code something like this:

 internal static void UpdateBrowser(long transactionId) { lock (connection) { if (connection.State == ConnectionState.Disconnected){ connection.Start().Wait(); } } hub.Invoke("UpdateTransactionStatus", transactionId).ContinueWith(task => { if (task.IsFaulted && task.Exception != null) { // log error } }); } 

Answer 2

By default, .NET allows you to use 2 simultaneous connections coming from client applications and 10 from ASP.NET applications. If you want to increase this number, set http://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.defaultconnectionlimit.aspx to a larger number. See if that helps.