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Exception thrown when calling async task on Winui C#
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Paul Harvey Chiverton Messina
5
Reputation points
Dear everybody.
Using Microsoft Visual Studio Community 2022 (64 bits) - Current Versión 17.9.3 on Windows 10 most recent update, Packaged WinUI with C#
I am programming from scratch a new program (WinUI with C#) to manage my motorized telescope and I am trying to communicate with my 32 but microcontrollers. I have succeded in listing all available serial ports. On startup I call the function that reads all available ports waiting on the task as I need the list of ports in order to select the last port I used (saved in a file) and select it on a combobox of available ports from the start. All goes well. ComboBox works, etc. I select a different port and close the program and this selected port is saved on my configuration file for next opening of the program.
The problem arises when in the program I click a button to update the list of serial ports just in case there is a new available port. This button calls a function Private void ActualizarPS(object sender, RoutedEventArgs e) which calls Task.Run(async () => { await ActualizarPuertosSerie(); }).Wait(); (the same way as at startup) but I get an exception thrown (at the end below) at this call.
Why? Any solution?
CODING
=============
public MainProgram()
{
this.InitializeComponent();
FUNCIONES.InicializarVariables(); // Inicialización variables GLOBALES del programa
Task.Run(async () => { await archivoConfiguracion(false); }).Wait(); // Leer archivo de configuración
Task.Run(async () => { await ActualizarPuertosSerie(); }).Wait(); // Actualizar / leer puertos serie disponibles
... }
private async Task ActualizarPuertosSerie()
{
if (GLOBALES.CloseProgramOK == false) { // Cierre programa no invocado
if (GLOBALES.AbiertoPuertoSerie == false)
{ // Puerto serie no está abierto
serialDeviceInfos = await DeviceInformation.FindAllAsync(SerialDevice.GetDeviceSelector());
PuertosSerieDisponibles.Clear();
PuertosSerieDisponibles.Add("NO COM");
foreach (DeviceInformation serialDeviceInfo in serialDeviceInfos)
{
try
{
SerialDevice serialDevice = await SerialDevice.FromIdAsync(serialDeviceInfo.Id);
if (serialDevice != null)
{
PuertosSerieDisponibles.Add(serialDevice.PortName);
serialDevice.Dispose();
}
}
catch (Exception)
{
// Error. Nothing for now
}
}
}
else
{
MostrarMensajes("PUERTO SERIE AÚN ABIERTO", "Debe cerrar el puerto serie\nantes de actualizar la lista.", 1);
}
}
}
// Rutina que actualiza los puertos serie disponibles en el selector combo
private void ActualizarPS(object sender, RoutedEventArgs e)
{
if (GLOBALES.AbiertoPuertoSerie == false) // Puerto serie no está abierto
{
Task.Run(async () => { await ActualizarPuertosSerie(); }).Wait(); // Actualizar / leer puertos serie disponibles
}
else
{
MostrarMensajes("PUERTO SERIE AÚN ABIERTO", "Debe cerrar el puerto serie\nantes de actualizar la lista.", 1);
}
}
EXCEPTION THROWN
==================================
System.AggregateException
HResult=0x80131500
Mensaje = One or more errors occurred. ()
Origen = System.Private.CoreLib
Seguimiento de la pila:
en System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
en System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
en System.Threading.Tasks.Task.Wait()
en StellaeTempus.MainProgram.ActualizarPS(Object sender, RoutedEventArgs e) en X:\OneDrive\Programación\StellaeTempus\StellaeTempus\StellaeTempus\MainProgram.xaml.cs: línea 326
en ABI.Microsoft.UI.Xaml.RoutedEventHandler.Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)
Esta excepción se generó originalmente en esta pila de llamadas:
[Código externo]
StellaeTempus.MainProgram.ActualizarPuertosSerie() en MainProgram.xaml.cs
StellaeTempus.MainProgram.ActualizarPS.AnonymousMethod__16_0() en MainProgram.xaml.cs
Excepción interna 1:
COMException:
Any help appreciated.
Best Regards
Paul Harvey Chiverton
Visual Studio
Windows App SDK
Windows App SDK
A set of Microsoft open-source libraries, frameworks, components, and tools to be used in apps to access Windows platform functionality on many versions of Windows. Previously known as Project Reunion.
745 questions
C#
C#
An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.
10,562 questions
{count} votes
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Roy Li - MSFT 32,721 Reputation points Microsoft Vendor2024-03-22T01:30:47.5333333+00:00 Could you please use standard async-await method instead of using
Task.Run? This will be help to check if the issue comes from theActualizarPuertosSeriemethod or the task itself.Besides, you could put your code snippet in Code Block when you ask your question.
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Roy Li - MSFT 32,721 Reputation points Microsoft Vendor
2024-04-02T02:05:59.0933333+00:00 Any updates about this issue?
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Paul Harvey Chiverton Messina 5 Reputation points
2024-04-04T08:09:41.3533333+00:00 Dear Li.
I changed the fucntion call to Private async Task ActualizarPuertosSerie() which was called with
Task.Run(async () => { await ActualizarPuertosSerie(); }).Wait();to
ActualizarPuertosSerie().Wait();and it hangs at startup (with the previous call at startup this didn't happen) and any time it is called for example with a button click event.
I don't know why as it seems it stays in an infinite loop with the
.Wait()or something regardless of the await inside the function.I have changed the header of the function to
private async void ActualizarPuertosSerie()and just call it with
ActualizarPuertosSerie();This call doesn't give any exceptions and works fine anywhere and doesn't hang. What I have had to do is much further after startup, on
Mainpage_Loaded()event call the function and theprivate void PuertoSerie_Changed(object sender, RoutedEventArgs e)(that is fired when changing the observable collection the comboBox is bound to) handles selecting previous COM port that is stored in my configuration file to select the previous session COM port used. This configuration file is loaded at startup and saved on exit each session with
Task.Run(async () => { await archivoConfiguracion(false); }).Wait();that does wait for the end of the execution of the function and doesn't throw any exceptions whenever called..
Somehow these async Task functions with an await inside them aren't working as expected when using .Wait() with them as the main program waits for some reason infinitely for it to finish and never finishes or goes in the await inside the function that should let the main program / thread continue. If you don't use the
Wait()with these Task functions the compiler informs you that the main program will continue even when the function hasn't finished as you aren't using Wait() but it stays in an infinite loop.In any case the workaround has worked not using
Wait()For now problem solved.
Thank you for your help.
This WinuUI has some things that are making it complicated to programm in comparision to WPF and threading tasks.
Your help very much appreciated.
Paul
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Roy Li - MSFT 32,721 Reputation points Microsoft Vendor
2024-04-04T08:22:57.43+00:00 I'm very glad to hear that. Yes,
task.wait()sometimes will cause deadlock. One of the best practices in asynchronous programming is using async all the way. There is a document here which you could refer to: Async/Await - Best Practices in Asynchronous Programming
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