C#•4w ago

Uncaught OperationCancelledException when shutting down IHostedService

Is there a way to detect that OperationCancelledException was thrown specifically due to application shutdown (e.g. pressing "stop" button in IDE)?

19 Replies

FusedQyou•4w ago

I assume the Run(Async) method throws this, so you can try-catch there

Unknown User•4w ago

Message Not Public

FusedQyou•4w ago

I assume the issue is the fact that the process cancels due to shutdown, and the question is how you would gracefully shut down when that happens

Unknown User•4w ago

Message Not Public

FusedQyou•4w ago

So how would you check IsCancellationRequested if the code throws Then it's too late

Unknown User•4w ago

Message Not Public

FusedQyou•4w ago

Yes so the code throws

Unknown User•4w ago

Message Not Public

FusedQyou•4w ago

So it should gracefully shutdown with a try-catch

Unknown User•4w ago

Message Not Public

FusedQyou•4w ago

No point in checking IsCancellationRequested when the exception already thrown

Unknown User•4w ago

Message Not Public

SilverShadeOP•4w ago

public abstract class BackgroundService : IHostedService
{
    private Task _executingTask;
    private readonly CancellationTokenSource _stoppingCts = new CancellationTokenSource();

    protected abstract Task ExecuteAsync(CancellationToken stoppingToken);

    public virtual Task StartAsync(CancellationToken cancellationToken)
    {
        _executingTask = ExecuteAsync(_stoppingCts.Token);
        return _executingTask.IsCompleted ? _executingTask : Task.CompletedTask;
    }

    public virtual async Task StopAsync(CancellationToken cancellationToken)
    {
        if (_executingTask == null)
            return;

        try
        {
            _stoppingCts.Cancel();
        }
        finally
        {
            await Task.WhenAny(_executingTask, Task.Delay(Timeout.Infinite, cancellationToken));
        }
    }

public abstract class BackgroundService : IHostedService
{
    private Task _executingTask;
    private readonly CancellationTokenSource _stoppingCts = new CancellationTokenSource();

    protected abstract Task ExecuteAsync(CancellationToken stoppingToken);

    public virtual Task StartAsync(CancellationToken cancellationToken)
    {
        _executingTask = ExecuteAsync(_stoppingCts.Token);
        return _executingTask.IsCompleted ? _executingTask : Task.CompletedTask;
    }

    public virtual async Task StopAsync(CancellationToken cancellationToken)
    {
        if (_executingTask == null)
            return;

        try
        {
            _stoppingCts.Cancel();
        }
        finally
        {
            await Task.WhenAny(_executingTask, Task.Delay(Timeout.Infinite, cancellationToken));
        }
    }

Cant share the original code since it’s proprietary, but the logic is roughly the same as here, taken from an open source article

Unknown User•4w ago

Message Not Public

SilverShadeOP•4w ago

Yeah it’s not in my app

Unknown User•4w ago

Message Not Public

SilverShadeOP•4w ago

Ig if i were to write pseudo code for it, the snippet i just sent would be it So yeah it best describes what is implemented in my code

Unknown User•4w ago

Message Not Public

SilverShadeOP•4w ago

Hmm yeah i’ll try to implement that, thanks!♥️

Gaming

Programming

Uncaught OperationCancelledException when shutting down IHostedService