Windows Store App StreamSoket DataReader.LoadAsync() ObjectDisposedException

Question

I have problems with Windows 8 UI application. I'm using client-server communication and client needs to check new messages all time. So I use such code, where _socket is a StreamSoket:

    private async static void MessageReceiver()
    {
        var dataReader = new DataReader(_socket.InputStream);
        dataReader.InputStreamOptions = InputStreamOptions.Partial;

        var stringHeader = await dataReader.LoadAsync(4);
        if (stringHeader != 0)
        {
            var bytes = new byte[4];
            dataReader.ReadBytes(bytes);
            var length = BitConverter.ToInt32(bytes, 0);

            var count = await dataReader.LoadAsync((uint) length);

            var result = dataReader.ReadString(count);

            ParseRequest(result);
        }

        dataReader.DetachStream();


        MessageReceiver();
    }

But in the second LoadAsync, when I try to read the string, I have ObjectDisposedException. Can you help me with it? I have no idea, why such exception is thrown. I've also tried to use DataReader.InputStream.ReadAsync(), but I also had such problem.

Does the exception happen in the dataReader.LoadAsync() call or the dataReader.ReadString() call? — atkretsch, Nov 13 '12 at 23:01
I've noticed, that it's happens, when I connect with another client (simple WPF application, which uses old sockets with ReadBytes(), and it's working fine, but Metro application falls). — Dmitriy Bondarchuk, Nov 14 '12 at 22:14
@AlexSorokoletov I have the same problem, have you found any solution yet ? — TootsieRockNRoll, Feb 04 '14 at 10:12
I can't remember how I fixed it in the end. I think we've refactored stream/socket usage and removed DetachStream calls. — Alex Sorokoletov, Feb 04 '14 at 15:26

score 2 · Answer 1 · answered Jan 30 '15 at 00:02

I know this is an old post but since I was having the same problem and figured it out I thought I would post the solution for anyone else that stumbles across this. Although I won't claim to know exactly what the cause of this problem is, since I'm primarily a C++ guy, the solution was fairly simple.

The way I fixed it was by declaring the DataReader as a class member, thereby extending it's scope

_socket= new StreamSocket();
_socket.Control.KeepAlive = true;
_socket.Control.NoDelay = true;
_socketReader = new DataReader(_socket.InputStream);
_socketReader.InputStreamOptions = InputStreamOptions.Partial;

My possibly incorrect understanding of the await keyword is that the call is basically put on a new thread and that the rest of the function will continue off on the previous thread. Since the DataReader was declared locally, it will go out of scope once the function completes, leaving the await thread to work off of a disposed object.

If anybody wants to clarify this it would be appreciated.

score 1 · Answer 2 · answered Oct 10 '14 at 04:29

1

Based of Alex Sorokoletov's last comment, my guess would be that the one of your important objects (probably the stream) would be disposed in the call to datareader.DetachStream();

answered Oct 10 '14 at 04:29

Noémie Lord

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Windows Store App StreamSoket DataReader.LoadAsync() ObjectDisposedException

2 Answers2