After migration to ASP Core3 this line freezes the web app startup process (with VS debug: browser had pop up but the page loading never ends)
serviceCollection.AddHostedService<BackgroundService>();
It works in Core 2.
I can't see any breaking changes related to AddHostedService in ASP Core3 documentation:
It seems like blocking background server StartAsync blocks the web app startup. May be something should be configured in WebHost to make StartAsync async again?
The background service code looks like:
public class MyBackgroundService : IHostedService
{
private readonly BackgroundServiceHandle backgroundServiceHandle;
private CancellationTokenSource tokenSource;
public MyBackgroundService (BackgroundServiceHandle backgroundServiceHandle) =>
this.backgroundServiceHandle = backgroundServiceHandle;
public async Task StartAsync(CancellationToken cancellationToken)
{
tokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
while (cancellationToken.IsCancellationRequested == false)
{
try
{
await Task.Delay(TimeSpan.FromSeconds(3), cancellationToken).ConfigureAwait(false);
// IMPORTANT: it seems that next line blocks the web app startup, but why this works in CORE 2?
var taskSettings = backgroundServiceHandle.Dequeue(tokenSource.Token);
// the work
}
catch (OperationCanceledException)
{
// execution cancelled
}
}
}
public Task StopAsync(CancellationToken cancellationToken)
{
tokenSource.Cancel();
return Task.CompletedTask;
}
}
public sealed class BackgroundServiceHandle : IDisposable
{
private readonly BlockingCollection<TaskSettings> blockingCollection;
public BackgroundServiceHandle() => blockingCollection = new BlockingCollection<TaskSettings>();
public void Enqueue(TaskSettings settings) => blockingCollection.Add(settings);
public TaskSettings Dequeue(CancellationToken token) => blockingCollection.Take(token);
public void Dispose()
{
blockingCollection.Dispose();
}
}
