What happens to debugger here?

[Brett]

I walk through the following code and when I reach the last line, which is
highlighted in yellow from the debugger, I step forward and nothing happens.
The yellow highlighted block goes away and the while loop is no longer
executed. The code is on a second thread. After stepping forward, focus
returns to the application or main form. There are no errors or exceptions.

While True
Try

If networkStream.CanWrite And networkStream.CanRead Then

networkStream = tcpClient.GetStream()

Dim bytes(tcpClient.ReceiveBufferSize) As Byte
networkStream.Read(bytes, 0,
tcpClient.ReceiveBufferSize)
I did this change to see exactly which part of the above line was causing
the problem. The debugger does the same thing on the last line here.

Dim mysize As Integer =
CInt(tcpClient.ReceiveBufferSize)
networkStream.Read(bytes, 0, mysize)

Any idea how I can trouble shoot this? Why does the debugger just suddenly
go away?

Thanks,
Brett

[Adam Goossens]

Brett,

Remember that NetworkStream.Read() is a blocking call. When
NetworkStream.Read() blocks, the debugger cannot continue because it's
waiting for the Read() call to complete.

Are you sure that data is read at all?

Regards,
-Adam.

Brett wrote:

I walk through the following code and when I reach the last line, which is
highlighted in yellow from the debugger, I step forward and nothing happens.
The yellow highlighted block goes away and the while loop is no longer
executed. The code is on a second thread. After stepping forward, focus
returns to the application or main form. There are no errors or exceptions.

While True
Try

If networkStream.CanWrite And networkStream.CanRead Then

networkStream = tcpClient.GetStream()

Dim bytes(tcpClient.ReceiveBufferSize) As Byte
networkStream.Read(bytes, 0,
tcpClient.ReceiveBufferSize)
I did this change to see exactly which part of the above line was causing
the problem. The debugger does the same thing on the last line here.

Dim mysize As Integer =
CInt(tcpClient.ReceiveBufferSize)
networkStream.Read(bytes, 0, mysize)

Any idea how I can trouble shoot this? Why does the debugger just suddenly
go away?

Thanks,
Brett

[Brett]

I'm not sure the data is read. Shouldn't it be read if the debugger comes
back? How do I tell?

Why would it start doing this all of the sudden? I do get data back from
the Listener but that was before this started happening. How can I be sure
the problem is on the client or listener side?

Thanks,
Brett
"Adam Goossens" <ad***********@gmail.com> wrote in message
news:%2****************@TK2MSFTNGP14.phx.gbl...

Brett,

Remember that NetworkStream.Read() is a blocking call. When
NetworkStream.Read() blocks, the debugger cannot continue because it's
waiting for the Read() call to complete.

Are you sure that data is read at all?

Regards,
-Adam.

Brett wrote:

I walk through the following code and when I reach the last line, which
is highlighted in yellow from the debugger, I step forward and nothing
happens. The yellow highlighted block goes away and the while loop is no
longer executed. The code is on a second thread. After stepping
forward, focus returns to the application or main form. There are no
errors or exceptions.

While True
Try

If networkStream.CanWrite And networkStream.CanRead Then

networkStream = tcpClient.GetStream()

Dim bytes(tcpClient.ReceiveBufferSize) As Byte
networkStream.Read(bytes, 0,
tcpClient.ReceiveBufferSize)
I did this change to see exactly which part of the above line was causing
the problem. The debugger does the same thing on the last line here.

Dim mysize As Integer =
CInt(tcpClient.ReceiveBufferSize)
networkStream.Read(bytes, 0, mysize)

Any idea how I can trouble shoot this? Why does the debugger just
suddenly go away?

Thanks,
Brett

[Adam Goossens]

Hi Brett,

It's probably a good bet that if the debugger can't advance past that
line, then no data is coming in. If you're expecting data to be coming
in at a constant rate, it sounds like a problem with the server.

If the debugger steps to the next line, one of two things has happened:
1) Data was read without problem, or,
2) The Read() call has returned 0 (zero) indicating that all data has
been read and the remote host has shut down the connection.

Since neither of those two is happening, it is fair enough to assume
that your listener is waiting for data to be received, but none is being
sent.

You might want to try stepping through your server code as well. If you
step through both of them at once you might be able to find the point
where something isn't quite right.

Let me know how you go.
Regards,
-Adam.
Brett wrote:

I'm not sure the data is read. Shouldn't it be read if the debugger comes
back? How do I tell?

Why would it start doing this all of the sudden? I do get data back from
the Listener but that was before this started happening. How can I be sure
the problem is on the client or listener side?

Thanks,
Brett

[Adam Goossens]

Hi Brett,

How do I debug two applications at the same time? Two instances of VS.NET?

Spot on. Run your server in one instance, your client in another, set
some breakpoints and let them go.

Has this problem always occurred, or is it a recent thing?

Regards,
-Adam.