How to gracefully shutdown server

How to gracefully close stream during host shutdown? i am always getting " The operation was canceled." exception on CTRL+C (Asp.NET core 3.1 gRPC template). `

        try
        {
            await foreach (var response in requestStream.ReadAllAsync(context.CancellationToken))
            {
                _ = Task.Run(() =>
                {
                    ProcessResponse(response);
                });
            }
        }

        catch (Exception) when (context.CancellationToken.IsCancellationRequested)
        {
            _logger.LogInformation("Server shutdown");
            
            //Graceful shutdown
        }

`

[JamesNK]

Yes its client streaming scenario. When I press Ctrl+C on server gRPC server console, its taking more time to stop server since cancellationToken is not triggered from client. I modified code as follows to close stream immediately (Using IHostApplicationLifeTime / IHostLifetime)

When you Ctrl+C Kestrel will attempt to gracefully shutdown. That means it will wait some time for requests that are in-progress to end. That is why you see a delay.

var cancellationSource = CancellationTokenSource.CreateLinkedTokenSource(
    context.CancellationToken, _lifetime.ApplicationStopping, _lifetime.ApplicationStopped);

This is good. The server will end reading from the stream when ApplicationStopping is triggered. The call then ends on the server and Kestrel stops quickly.

I don’t think you need ApplicationStopped:

var cancellationSource = CancellationTokenSource.CreateLinkedTokenSource(
    context.CancellationToken, _lifetime.ApplicationStopping);

[rajeshaz09]

Hello @rajeshaz09, I am a gRPC user, not an author of gRPC but let me try to handle the question.

Answering your question is not related to the specific use case, but based on code I am assuming you have:

• client streaming scenario,
• an application that is closed using CTRL+C is a client application,

I believe that you are not required to call any method on stream, to have it closed or disposed as it is already aware of being cancelled. Moreover, the stream was responsible for throwing an OperationCanceledException you have catched. Let me know if it solves your concerns.

I think that the log information (“Server shutdown”) is a bit misleading as you are not doing server application shutdown, but rather reacting to RPC termination.

Thanks @wicharypawel Yes its client streaming scenario. When I press Ctrl+C on server gRPC server console, its taking more time to stop server since cancellationToken is not triggered from client. I modified code as follows to close stream immediately (Using IHostApplicationLifeTime / IHostLifetime)

`

        var cancellationSource = CancellationTokenSource.CreateLinkedTokenSource(
            context.CancellationToken, _lifetime.ApplicationStopping, _lifetime.ApplicationStopped);

        try
        {
            await foreach (var response in _requestStream.ReadAllAsync(cancellationSource.Token))
            {
                _ = Task.Run(() =>
                {
                    ProcessResponse(response);
                });
            }
        }

        catch (Exception) when (cancellationToken.IsCancellationRequested)
        {
            //Graceful closing of streaming in following cases
            //1) host stopping
            //2) client ended stream
        }

`