InvalidOperationException: There is already one outstanding 'SendAsync' call for this WebSocket instance

[djonasdev]

This issue relates to #260

Actually the GraphQLRequest are processed parallel and not as you want in serial.

The Issue seems to be in https://github.com/graphql-dotnet/graphql-client/blob/master/src/GraphQL.Client/Websocket/GraphQLHttpWebSocket.cs#L81

_requestSubscription = _requestSubject.Select(SendWebSocketRequestAsync).Concat().Subscribe();

changing back to https://github.com/haprotec/graphql-client/blob/subscriptions-api/src/GraphQL.Client/Http/GraphQLHttpWebSocket.cs#L42 should fix this problem.

_requestSubscription = _requestSubject.Select(request => Observable.FromAsync(() => _sendWebSocketRequest(request))).Concat().Subscribe();

Old version

class Program
{
	static void Main(string[] args)
	{
		try
		{
			Console.WriteLine("started");
			var subject = new Subject<int>();
			var subscription = subject.Select(i => Observable.FromAsync(() => FooAsync(i))).Concat().Subscribe();

			for (int i = 0; i < 10; i++)
			{
				Console.WriteLine($"add item nr. {i}");
				subject.OnNext(i);
			}
			Console.WriteLine("all items added");
		}
		catch (Exception e)
		{
			Console.WriteLine(e);
		}
		Console.WriteLine("Press any key to exit.");
		Console.ReadKey();
	}

	public static async Task<int> FooAsync(int i)
	{
		await Task.Delay(TimeSpan.FromSeconds(1));
		Console.WriteLine($"{DateTime.Now.ToLongTimeString()}: item {i} elapsed");
		return i;
	}
}

started
add item nr. 0
add item nr. 1
add item nr. 2
add item nr. 3
add item nr. 4
add item nr. 5
add item nr. 6
add item nr. 7
add item nr. 8
add item nr. 9
all items added
Press any key to exit.
08:49:19: item 0 elapsed
08:49:20: item 1 elapsed
08:49:21: item 2 elapsed
08:49:22: item 3 elapsed
08:49:23: item 4 elapsed
08:49:24: item 5 elapsed
08:49:25: item 6 elapsed
08:49:26: item 7 elapsed
08:49:27: item 8 elapsed
08:49:28: item 9 elapsed

New version

class Program
{
	static void Main(string[] args)
	{
		try
		{
			Console.WriteLine("started");
			var subject = new Subject<int>();
			var subscription = subject.Select(FooAsync).Concat().Subscribe();

			for (int i = 0; i < 10; i++)
			{
				Console.WriteLine($"add item nr. {i}");
				subject.OnNext(i);
			}
			Console.WriteLine("all items added");
		}
		catch (Exception e)
		{
			Console.WriteLine(e);
		}
		Console.WriteLine("Press any key to exit.");
		Console.ReadKey();
	}

	public static async Task<int> FooAsync(int i)
	{
		await Task.Delay(TimeSpan.FromSeconds(1));
		Console.WriteLine($"{DateTime.Now.ToLongTimeString()}: item {i} elapsed");
		return i;
	}
}

started
add item nr. 0
add item nr. 1
add item nr. 2
add item nr. 3
add item nr. 4
add item nr. 5
add item nr. 6
add item nr. 7
add item nr. 8
add item nr. 9
all items added
Press any key to exit.
08:50:08: item 0 elapsed
08:50:08: item 1 elapsed
08:50:08: item 2 elapsed
08:50:08: item 3 elapsed
08:50:08: item 5 elapsed
08:50:08: item 6 elapsed
08:50:08: item 7 elapsed
08:50:08: item 4 elapsed
08:50:08: item 9 elapsed
08:50:08: item 8 elapsed