C# connectivity watcher causes lots of IDE output

[jskeet]

Please answer these questions before submitting your issue.

What version of gRPC and what language are you using?

C# running in VS 15.5.1, targeting net461, tested with gRPC 1.7.3 and 1.8.0-pre2.

What operating system (Linux, Windows, …) and version?

Windows 10, with Creators Update

What runtime / compiler are you using (e.g. python version or version of gcc)

Visual Studio C# compiler

What did you do?

Project file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net461</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Grpc.Core" Version="1.8.0-pre2" />
    <PackageReference Include="Grpc.Auth" Version="1.8.0-pre2" />
  </ItemGroup>
</Project>

Program file:

using Grpc.Auth;
using Grpc.Core;
using System;

class Program
{
    static void Main()
    {
        var endpoint = "datastore.googleapis.com:443";
        var auth = GoogleGrpcCredentials.GetApplicationDefaultAsync().Result;
        var channel = new Channel(endpoint, auth);
        Console.ReadLine();
        GC.KeepAlive(channel);
    }
}

Run in the debugger - it doesn't matter whether it's a Release or Debug configuration build.

What did you expect to see?

Relatively little output in the VS Output window

What did you see instead?

Once per second:

Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in mscorlib.dll

If the TaskCanceledException is set to "break when thrown", the stack trace shows:

mscorlib.dll!System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(System.Threading.Tasks.Task task)
mscorlib.dll!System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task task)
Grpc.Core.dll!Grpc.Core.Channel.RunConnectivityWatcherAsync()	Unknown	No symbols loaded.
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx)
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx)
mscorlib.dll!System.Runtime.CompilerServices.AsyncMethodBuilderCore.MoveNextRunner.Run()
mscorlib.dll!System.Runtime.CompilerServices.AsyncMethodBuilderCore.OutputAsyncCausalityEvents.AnonymousMethod__0()
mscorlib.dll!System.Runtime.CompilerServices.TaskAwaiter.OutputWaitEtwEvents.AnonymousMethod__0()
mscorlib.dll!System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(System.Action action, bool allowInlining, ref System.Threading.Tasks.Task currentTask)
mscorlib.dll!System.Threading.Tasks.Task.FinishContinuations()
mscorlib.dll!System.Threading.Tasks.Task<System.__Canon>.TrySetCanceled(System.Threading.CancellationToken tokenToRecord, object cancellationException)
mscorlib.dll!System.Threading.Tasks.TaskCompletionSource<object>.TrySetCanceled(System.Threading.CancellationToken cancellationToken)
mscorlib.dll!System.Threading.Tasks.TaskCompletionSource<System.__Canon>.SetCanceled()
Grpc.Core.dll!Grpc.Core.Internal.BatchContextSafeHandle.Grpc.Core.Internal.IOpCompletionCallback.OnComplete(bool success)	Unknown	No symbols loaded.
Grpc.Core.dll!Grpc.Core.Internal.GrpcThreadPool.RunCompletionQueueEventCallback(Grpc.Core.Internal.IOpCompletionCallback callback, bool success)	Unknown	No symbols loaded.
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx)
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx)
mscorlib.dll!System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
mscorlib.dll!System.Threading.ThreadPoolWorkQueue.Dispatch()

Looking at the code involved, the exception is being caught - it's not clear whether there's some way to avoid it being shown in the IDE output window.

[jtattermusch]

Also see #13227