[wasm-mt] JSImport and JSExport marshaler infrastructure is not initialized on web worker threads

[thaystg]

Assert failed: ERR41: Unknown converter for type 13

To reproduce:

• build.cmd mono+libs -os browser /p:WasmEnableThreads=true

• dotnet test src/mono/wasm/debugger/DebuggerTestSuite --filter DebuggerTests.MiscTests.InspectTaskAtLocals -e RuntimeConfiguration=Debug -e Configuration=Debug -e DebuggerHost=chrome -e WasmEnableThreads=true (only to build)

• Go to folder and run:

cd \artifacts\bin\debugger-test\Debug\AppBundle

..\..\..\..\..\dotnet.cmd serve  -h "Cross-Origin-Opener-Policy:same-origin" -h "Cross-Origin-Embedder-Policy:require-corp" -p 9400
Open on chrome: http://localhost:9400/debugger-driver.html

• Open Inspector
• Go to Watch and run this command: invoke_static_method_async('[debugger-test] InspectTask:RunInspectTask')

IMPORTANT: This is not using anything related to our debugger, because we are not using the remote debugging and the browser debug proxy.

As discussed with Pavel this is expected to not work.

This is the C# code executed:

public class WeatherForecast
{
    public DateTime Date { get; set; }

    public int TemperatureC { get; set; }

    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);

    public string Summary { get; set; }
}

public class InspectTask
{
    public static async System.Threading.Tasks.Task RunInspectTask()
    {
        WeatherForecast[] forecasts = null;
        var httpClient = new System.Net.Http.HttpClient();
        var getJsonTask = httpClient.GetFromJsonAsync<WeatherForecast[]>("http://localhost:9400/weather.json");
        try
        {
            await getJsonTask.ContinueWith(t =>
                {
                    int a = 10;
                    Console.WriteLine(a);
                    if (t.IsCompletedSuccessfully)
                        forecasts = t.Result;

                    if (t.IsFaulted)
                        throw t.Exception!;
                });
        }
        catch (Exception ex)
        {
            Console.WriteLine($"error {ex}");
            return;
        }
    }
}

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Issue Details

---

To reproduce:

• build.cmd mono+libs -os browser /p:WasmEnableThreads=true

• dotnet test src/mono/wasm/debugger/DebuggerTestSuite --filter DebuggerTests.MiscTests.InspectTaskAtLocals -e RuntimeConfiguration=Debug -e Configuration=Debug -e DebuggerHost=chrome -e WasmEnableThreads=true (only to build)

• Go to folder and run:

cd \artifacts\bin\debugger-test\Debug\AppBundle

..\..\..\..\..\dotnet.cmd serve  -h "Cross-Origin-Opener-Policy:same-origin" -h "Cross-Origin-Embedder-Policy:require-corp" -p 9400
Open on chrome: http://localhost:9400/debugger-driver.html

• Open Inspector
• Go to Watch and run this command: invoke_static_method_async('[debugger-test] InspectTask:RunInspectTask')

IMPORTANT: This is not using anything related to our debugger, because we are not using the remote debugging and the browser debug proxy.

As discussed with Pavel this is expected to not work.

This is the C# code executed:

public class WeatherForecast
{
    public DateTime Date { get; set; }

    public int TemperatureC { get; set; }

    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);

    public string Summary { get; set; }
}

public class InspectTask
{
    public static async System.Threading.Tasks.Task RunInspectTask()
    {
        WeatherForecast[] forecasts = null;
        var httpClient = new System.Net.Http.HttpClient();
        var getJsonTask = httpClient.GetFromJsonAsync<WeatherForecast[]>("http://localhost:9400/weather.json");
        try
        {
            await getJsonTask.ContinueWith(t =>
                {
                    int a = 10;
                    Console.WriteLine(a);
                    if (t.IsCompletedSuccessfully)
                        forecasts = t.Result;

                    if (t.IsFaulted)
                        throw t.Exception!;
                });
        }
        catch (Exception ex)
        {
            Console.WriteLine($"error {ex}");
            return;
        }
    }
}

Author:	thaystg
Assignees:	pavelsavara
Labels:	arch-wasm, feature-request, area-System.Runtime.InteropServices.JavaScript
Milestone:	8.0.0

[pavelsavara]

invoke_static_method is legacy JS interop. It is not supported on any other than main thread. Here it's used by the test code.
The JSExport/JSImport could be used on threads which were created with WebWorker API, but that's out of scope for Net8.

@thaystg could you please describe why the unit test is sending the commands to any other than main thread ? Is that intentional ? Or am I confused about it ?