C#•2mo 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•2mo ago

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

Unknown User•2mo ago

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FusedQyou•2mo 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•2mo ago

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FusedQyou•2mo ago

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

Unknown User•2mo ago

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FusedQyou•2mo ago

Yes so the code throws

Unknown User•2mo ago

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FusedQyou•2mo ago

So it should gracefully shutdown with a try-catch

Unknown User•2mo ago

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FusedQyou•2mo ago

No point in checking IsCancellationRequested when the exception already thrown

Unknown User•2mo ago

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SilverShadeOP•2mo 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•2mo ago

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SilverShadeOP•2mo ago

Yeah it’s not in my app

Unknown User•2mo ago

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SilverShadeOP•2mo 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•2mo ago

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SilverShadeOP•2mo ago

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

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Uncaught OperationCancelledException when shutting down IHostedService

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