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Websocket makes server slow down download speed

I developed a websocket on server & client machines using Microsoft websocket.
Clients upload and download bookings with the server if there is any change from both sides. It is a real time communication between clients and server using Microsoft websocket.
It works fine with a few clients only. However, when I set up for around 100 clients. it makes download speeds of the server slow down. Normally, the internet speed of the server is around 900 Mbps and it drops to 50Mbps.
I configured websocket on IIS.  I checked on IIS, worker processes use too much CPU and bandwidth, CPU sometimes up to 100%. 
How can I avoid this performance degradation?
Here is the sample of my code
public class booking : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
try
{
if (context.IsWebSocketRequest)
{
context.AcceptWebSocketRequest(new MicrosoftWebsockets());
}
}
catch (Exception e)
{
MicrosoftWebsockets.WriteErrorWebSocket(e.Message, tillNumber);
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
public class MicrosoftWebsockets : WebSocketHandler
{
private static WebSocketCollection clients = new WebSocketCollection();
public string businessid;
public override void OnOpen()
{
try
{
..............
}
catch (Exception e)
{
WriteLogError(e.Message);
}
}
public override void OnMessage(string message)
{
try
{
if (!string.IsNullOrEmpty(message))
{
ReceiveMessage(message);
}
}
catch (Exception e)
{
WriteLogError(e.Message);
}
}
public void ReceiveMessage(string message)
{
try
{
dynamic json = JsonConvert.DeserializeObject<dynamic>(message);
var s = json.method;
if (s == "updatechanged")
{
updatechanged(this.businessid, json);
}
}
catch (Exception e)
{
WriteLogError(e.Message);
}
}
public async Task updatechanged(string businessid, dynamic json, string message)
{
List<Appointments> appts = DataHelper.ConvertJonToAppointmentList(businessid, message);
if (appts != null && appts.Count > 0)
{
var resltList = await UpdateAppointment(businessid, appts);
JArray props = new JArray();
if (resltList != null && resltList.Count > 0)
{
foreach (var p in resltList)
{
string output = JsonConvert.SerializeObject(p);
props.Add(output);
}
JObject joe = new JObject();
joe["jsonrpc"] = "2.0";
joe["id"] = json.id;
joe["method"] = "serverreturnappointment";
joe.Add(new JProperty("params", props));
string result = JsonConvert.SerializeObject(joe);
clients.SingleOrDefault(r => ((MicrosoftWebsockets)r).businessid == this.businessid).Send(result);
}
}
}
}

C# SignalR2 receive online user list from server

I have created a chat using SignalR2. The client and server itself works fine. Now, I'm trying to implement a 'users online' function. The server code seems about right, but I'm struggling to make the client receive the data that the server pushes back to the client.
This is the server code below:
public static List<string> Users = new List<string>();
public void Send(string name, string message)
{
// Call the broadcastMessage method to update clients.
Clients.All.broadcastMessage(name, message);
Clients.All.addMessage(name, message);
}
public void SendUserList(List<string> users)
{
var context = GlobalHost.ConnectionManager.GetHubContext<chatHub>();
context.Clients.All.updateUserList(users);
}
public override Task OnConnected()
{
string clientId = GetClientId();
//if (Users.IndexOf(clientId) == -1)
//{
Users.Add(clientId);
//}
SendCount(Users.Count);
return base.OnConnected();
}
public override Task OnDisconnected(bool stopCalled)
{
System.Diagnostics.Debug.WriteLine("Disconnected");
SendCount(Users.Count);
return base.OnDisconnected(stopCalled);
}
private string GetClientId()
{
string clientId = "";
if (Context.QueryString["clientId"] != null)
{
// clientId passed from application
clientId = this.Context.QueryString["clientId"];
}
if (string.IsNullOrEmpty(clientId.Trim()))
{
clientId = Context.ConnectionId;
}
return clientId;
}
public void SendCount(int count)
{
// Call the addNewMessageToPage method to update clients.
var context = GlobalHost.ConnectionManager.GetHubContext<chatHub>();
context.Clients.All.updateUsersOnlineCount(count);
}
Below is the client code for connecting / receiving messages:
public static async void ConnectAsync(RadChat ChatInternal)
{
ChatInternal.Author = new Author(null, Varribles.Agent);
var querystringData = new Dictionary<string, string>();
querystringData.Add("clientId", Varribles.Agent);
Connection = new HubConnection(ServerURI, querystringData);
HubProxy = Connection.CreateHubProxy("chatHub");
//Handle incoming event from server: use Invoke to write to console from SignalR's thread
HubProxy.On<string, string>("AddMessage", (name, message) =>
ChatInternal.Invoke((Action)(() =>
Backend.GET.Messages(ChatInternal)
)));
try
{
await Connection.Start();
Backend.GET.Messages(ChatInternal);
}
catch (System.Net.Http.HttpRequestException)
{
//No connection: Don't enable Send button or show chat UI
return;
}
}
Now, my question is, how can I retrieve the 'Users' list from the server?
Thanks in advance

UWP AppServiceConnection - SendResponseAsync returns AppServiceResponseStatus.Failure

I'm trying to create a UWP service app on the Raspberry Pi3 which provides the access to the on board UART. I'm facing an issue about the AppConnection Request/response.
this is the service method that handles the incoming requests from client apps
internal class Inbound
{
public static async void OnRequestReceived(AppServiceConnection sender, AppServiceRequestReceivedEventArgs args)
{
var messageDeferral = args.GetDeferral();
var response = new ValueSet();
bool success = false;
var msg = args.Request.Message.Keys;
if (args.Request.Message.TryGetValue(ServiceApiRequests.Keys.Command, out object command))
{
try
{
switch (command)
{
case ServiceApiRequests.CommandValues.UartWrite:
if (args.Request.Message.TryGetValue(ServiceApiRequests.Keys.UartTxBuffer, out object txBuffer))
{
string rxBuff = "";
success = await Pi3.Peripherals.Uart.GerInstance(57600).Write((string)txBuffer);
if (success)
{
Debug.WriteLine("Tx: " + (string)txBuffer);
if (args.Request.Message.TryGetValue(ServiceApiRequests.Keys.ReadUartResponse, out object getResponse))
{
if ((string)getResponse == ServiceApiRequests.ReadUartResponse.Yes)
{
rxBuff = await Pi3.Peripherals.Uart.GerInstance(57600).Read();
Debug.WriteLine("Rx: " + rxBuff);
}
}
}
response.Add(ServiceApiRequests.Keys.UartRxBuffer, rxBuff);
}
break;
}
}
catch (Exception ex)
{
success = false;
}
}
response.Add(new KeyValuePair<string, object>(ServiceApiRequests.Keys.Result, success ? ServiceApiRequests.ResultValues.Ok : ServiceApiRequests.ResultValues.Ko));
var result = await args.Request.SendResponseAsync(response);
if (result == AppServiceResponseStatus.Failure)
{
Debug.WriteLine("Failed to send the response");
}
messageDeferral.Complete();
}
}
As you can figure out, the Uart class is get using the Singleton pattern using the method Pi3.Peripherals.Uart.GerInstance(57600).
Following the code i using for send the request from the client app.
public static class Uart
{
public static IAsyncOperation<string> SendCommand(this AppServiceConnection DriverControllerConnection, string txBuffer, string awaitResponse = ServiceApiRequests.ReadUartResponse.Yes)
{
return _SendCommand(DriverControllerConnection, txBuffer, awaitResponse).AsAsyncOperation();
}
private static async Task<string> _SendCommand(AppServiceConnection DriverControllerConnection, string txBuffer, string awaitResponse)
{
AppServiceResponse response = null;
string response_str = "";
try
{
if (DriverControllerConnection != null)
{
response = await DriverControllerConnection.SendMessageAsync(new ServiceApiRequests.UartWrite().GetCommand(txBuffer, awaitResponse));
if (response.Status == AppServiceResponseStatus.Success)
{
if (response.Message.TryGetValue(ServiceApiRequests.Keys.Result, out object result))
{
if ((string)result == ServiceApiRequests.ResultValues.Ok && awaitResponse == ServiceApiRequests.ReadUartResponse.Yes)
{
response_str = response.Message[ServiceApiRequests.Keys.UartRxBuffer] as string;
}
}
}
}
}
catch (Exception ex)
{
// TODO: log
}
return response_str;
}
}
The system works well just for a while, until i have response.Status == AppServiceResponseStatus.Success , then the result of the request changes and it becomes AppServiceResponseStatus.Failure. This way the program counter never steps into the condition if (response.Status == AppServiceResponseStatus.Success).
Any idea about the cause?
Thank you so much for the help.
EDIT
Follow the suggestions, i added an handler for the ServiceClosed event. This is the main class.
public sealed class DriverListener : IBackgroundTask
{
private BackgroundTaskDeferral backgroundTaskDeferral;
private AppServiceConnection appServiceConnection;
public void Run(IBackgroundTaskInstance taskInstance)
{
backgroundTaskDeferral = taskInstance.GetDeferral();
// taskInstance.Canceled += OnTaskCanceled;
var triggerDetails = taskInstance.TriggerDetails as AppServiceTriggerDetails;
appServiceConnection = triggerDetails.AppServiceConnection;
appServiceConnection.RequestReceived += Inbound.OnRequestReceived;
appServiceConnection.ServiceClosed += OnTaskCanceled;
}
private void OnTaskCanceled(AppServiceConnection sender, AppServiceClosedEventArgs reason)
{
if (this.backgroundTaskDeferral != null)
{
Debug.WriteLine("ServiceClosed");
// Complete the service deferral.
this.backgroundTaskDeferral.Complete();
}
}
}
Placing a breakpoint in this function, i see that it was never triggered.
The app connection is opened using the singleton pattern, and putted in a dll that i use in the client app
public static AppServiceConnection GetDriverConnectionInstance()
{
if (_DriverConnectionInstance == null)
{
try
{
_DriverConnectionInstance = OpenDriverConnection().AsTask().GetAwaiter().GetResult();
}
catch
{
}
}
return _DriverConnectionInstance;
}
I also add a Request to the service that toggles a led, and i noticed that the led status changes but the response from the app service is still "Failure" and the message is null.

The AppService has a default lifetime of 25sec, unless it is being requested by the foreground experience. When the service shuts down the connection, your client process will receive the ServiceClosed event, so you know you will need to reopen the connection the next time you want to send a request.

WCF service server throws an exception Cannot access a disposed object

So my service is a simple chat application between two wcf clients. Event callback works when I call events. After I close my client and run it again, and write a message again (to call the event) it throws me exception:
An exception of type 'System.ObjectDisposedException' occurred in
RussianRouletteServiceLibrary.dll but was not handled in user code
Additional information: Cannot access a disposed object.
The code for my service callback is as follows:
private static Action<User, UMessage> gameChat = delegate { };
public void Play()
{
IGameCallback subscriber =
OperationContext.Current.GetCallbackChannel<IGameCallback>();
gameChat += subscriber.PlayerSentMessage;
}
This is the event trigger:
public void SendMessage(User user, UMessage message)
{
try
{
gameChat(user, message);
}
catch (Exception ex)
{
throw ex;
}
}
I get this error every time I .ChannelFactory.Close(); .Close(); the client while closing form event is happening.
Is there anyone that knows how to fix this and is willing to share his knowledge?
Thank you in advance!
EDIT #1
This is the code of the client when it opens:
ConcurrencyMode.Multiple,
UseSynchronizationContext = false)]
public partial class GameForm : Form, IGameCallback
{
#region IGame Callbacks
public void PlayerSentMessage(User user, UMessage message)
{
string nickname = user.NickName == clientUser.NickName ? "You" : user.NickName;
this.Invoke(new MethodInvoker(() => lb_ChatBox.Items.Add(nickname + " : " + message.MessageContent)));
}
#endregion
private GameClient _gameClient = null;
private InstanceContext _instance = null;
private User clientUser = new User(){ Email = "zigm4s#gmail.com", Id = 0, FirstName = "Zigmas", LastName = "Slusnys", NickName = "Ziggy", Password = "test123"};
public GameForm()
{
string state;
if (_gameClient != null)
{
MessageBox.Show("nelygu null");
MessageBox.Show(_gameClient.State.ToString());
//_gameClient = new GameClient(new InstanceContext(this));
}
else
{
_gameClient = new GameClient(new InstanceContext(this));
MessageBox.Show(_gameClient.State.ToString());
}
InitializeComponent();
try
{
_gameClient.Open();
_gameClient.Play();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
This is when the client form is closing.
private void GameForm_FormClosing(object sender, FormClosingEventArgs e)
{
try {
if (_gameClient.State != System.ServiceModel.CommunicationState.Faulted)
{
MessageBox.Show("Closing client");
_gameClient.ChannelFactory.Close();
_gameClient.Close();
}
else
{
MessageBox.Show("Aborting client");
_gameClient.Abort();
}
}
catch(Exception ex)
{ MessageBox.Show(ex.ToString());}
}
EDIT #2
I found the mistake, on the service side i had delegates that were static. It doesn't throw this error when it's not static.

Making throwing exceptions work

I've been trying to write a small program with these instructions:
In this assignment you should write a simple web application with one link on the front page of the web. If the link is clicked, the user will simply be routed to the front page again (using RedirectToAction). However, occasionally, the action method might throw an exception (but not always). Occasionally (one in every 5 occasions) the method should throw an ArgumentException, and occasionally (again, in maybe 1 in a 5), it should throw a custom Exception object you should declare yourself, called MyApplicationException.
In HomeController I have:
public class HomeController : Controller
{
List<Logger> m_loggers = new List<Logger>();
protected override void OnException(ExceptionContext fc)
{
base.OnException(fc);
Exception ex = fc.Exception;
Logger.Instance.Log(ex);
}
public ActionResult Index()
{
string strLogFile = System.Configuration.ConfigurationManager.AppSettings["LogFile"];
string strEmail = System.Configuration.ConfigurationManager.AppSettings["Email"];
try
{
RedirectToAction("Index");
using(MailMessage message = new MailMessage())
{
message.To.Add(strEmail);
message.Subject = "Villuskilaboð";
message.Body = "Upp hefur komið villa frá Skilaverkefni 4!";
using(SmtpClient client = new SmtpClient())
{
client.EnableSsl = true;
client.Send(message);
}
}
}
catch(Exception ex)
{
Random r = new Random();
int rand = r.Next(1000);
if(rand % 5 == 0)
{
throw new System.ArgumentException("Randon villuskilaboð handa þér!");
}
Debug.WriteLine(ex.Message +
Environment.NewLine +
ex.StackTrace);
}
return View();
}
Logger class:
public class Logger
{
List<LogMedia>m_loggers = new List<LogMedia>();
private static Logger theInstance = null;
public static Logger Instance
{
get
{
if (theInstance == null)
{
theInstance = new Logger();
}
return theInstance;
}
}
private Logger()
{
m_loggers = new List<LogMedia>();
//m_loggers.Add(new TextFileLogMedia { });
//m_loggers.Add(new EmailLogMedia { });
}
public void Log(Exception ex)
{
foreach(LogMedia log in m_loggers)
{
log.LogMessage(ex.Message + Environment.NewLine);
}
}
}
LogMedia
public class LogMedia
{
public virtual void LogMessage(string Message)
{
}
public class OutputWindowLogMedia: LogMedia
{
public override void LogMessage(string Message)
{
System.Diagnostics.Debug.WriteLine(Message);
}
}
public class TextFileLogMedia: LogMedia
{
public override void LogMessage(string Message)
{
//File.AppendAllText("c:\\Temp.Log.txt", Message);
}
}
public class EmailLogMedia: LogMedia
{
public override void LogMessage(string Message)
{
}
}
}
I´m stuck for now and seems not getting it to work, my Visual Studio crash and I get error up, don't think that is the exception, I´m so new to it so maybe it´s the box that should come up :) But the email never get to my account.
What am I still missing to make everything work? I know the file-thing isn't in this code, trying to make the other things to work first.
I've added information about my eMail in web.config.

You really need to rework your Index() method. I'm not in front of my computer with Visual Studio, but I'm surprised you code gets past the first line in your try. Having the RedirectToAction("Index") should throw a warning that the rest of the method will never be reached, and create an infinite loop when you try to access the method. The RedirectToAction("Index")` you have in your code does nothing as you don't return the results of that. Thank you Erik Noren
This would be how I'd structure your method instead:
public ActionResult Index() {
// No need to go higher, as it's always just as random with a modulo
int rnd = (new Random()).Next(5);
try {
switch (rnd) {
case 1: // Or any of the 5 numbers you want.
throw new ArgumentException();
case 4: // Again, any of the 5 numbers
throw new MyApplicationException();
default:
return RedirectToAction("Index");
}
}
catch (Exception ex) {
// Do your error logging here.
}
}