Threading Issue

13 May 2005 11:56 PM

Mythran

Part #1:
I have a Thread, MainThread, and a child thread that is started in the
MainThread called ChildThread.

I have a DataSet created in the MainThread in which needs to be passed to
the ChildThread. The ChildThread needs to update the DataSet with new data.
The MainThread, after the ChildThread is finished, needs to continue on it's
merry way updating the DataSet.

Part #2:
I have MainThread and ChildThread ... in ChildThread, I need to create a
DataSet and/or a DataTable. The DataSet then needs to be passed to the
MainThread and then bound to either a DataGrid or Crystal Report...

I have tried both of the above questions but seem to get the same result
every time. Something about can't reference an object created on a
different thread. It was some time ago, and I just remembered about it and
am now curious. I can try setting up a project and duplicating my problems
again if need be...but hopefully there is a short/semi-short method that can
be described using pseudo/semi-pseudo code...

The problem is for C# or VB.Net, either will solve for the other...as it
should be, if any examples/code is given.

Thanks!

Mythran

14 May 2005 12:34 AM

Lebesgue

This seems like homework.
Do you want us to solve your homework for you?

Show quoteHide quote

"Mythran" <kip_potter@hotmail.comREMOVETRAIL> wrote in message
news:OkpdfdBWFHA.3280@TK2MSFTNGP09.phx.gbl...
> Part #1:
> I have a Thread, MainThread, and a child thread that is started in the
> MainThread called ChildThread.
>
> I have a DataSet created in the MainThread in which needs to be passed to
> the ChildThread. The ChildThread needs to update the DataSet with new
data.
> The MainThread, after the ChildThread is finished, needs to continue on
it's
> merry way updating the DataSet.
>
>
> Part #2:
> I have MainThread and ChildThread ... in ChildThread, I need to create a
> DataSet and/or a DataTable. The DataSet then needs to be passed to the
> MainThread and then bound to either a DataGrid or Crystal Report...
>
> I have tried both of the above questions but seem to get the same result
> every time. Something about can't reference an object created on a
> different thread. It was some time ago, and I just remembered about it
and
> am now curious. I can try setting up a project and duplicating my
problems
> again if need be...but hopefully there is a short/semi-short method that
can
> be described using pseudo/semi-pseudo code...
>
> The problem is for C# or VB.Net, either will solve for the other...as it
> should be, if any examples/code is given.
>
> Thanks!
>
> Mythran
>

14 May 2005 5:16 AM

Dave

"Mythran" <kip_potter@hotmail.comREMOVETRAIL> wrote in message
news:OkpdfdBWFHA.3280@TK2MSFTNGP09.phx.gbl...
> Part #1:
> I have a Thread, MainThread, and a child thread that is started in the
> MainThread called ChildThread.
>
> I have a DataSet created in the MainThread in which needs to be passed to
> the ChildThread. The ChildThread needs to update the DataSet with new
> data. The MainThread, after the ChildThread is finished, needs to continue
> on it's merry way updating the DataSet.

Take a look at this...not a difficult job i think:

///////////////////////////////////////////////////////////
class Application
{
void MainJob()
{
   Thread.CurrentThread.Name = "Main thread";
   ds = new DataSet();
   ds.Create();
   Thread th = new Thread(new ThreadStart(this.ChildJob));
   th.Name = "Child thread";
   th.Start();
   th.Join();
   ds.Update();
   //....
}
void ChildJob()
{
   ds.Update();
}
DataSet ds; // a shared dataset
}
}

public class DataSet
{
public DataSet()
{
   Console.WriteLine("Dateset instantiated on thread: {0}",
    Thread.CurrentThread.Name);
}
public void Create()
{
   Console.WriteLine("DataSet created on thread: {0}" ,
    Thread.CurrentThread.Name);
}
public void Update()
{
   Console.WriteLine("DataSet updated on thread: {0}",
    Thread.CurrentThread.Name);
}
}

///////////////////////////////////////////////
If you are afraid of multiple access to your dataset by many thread, simply
use the lock(this) statement (Monitor.Enter(....) and Monitor.Exit() in VB)