Handling exceptions in multithreaded dll

[serializer]

I have created a multithreaded dll which I am referencing in another project. I have created my own exceptions inheriting from Exception or ApplicationException object.

The problem I have is that try-catch does not work when it happens in another thread, below in the dll. How can I catch these errors, do I have to raise the errors to the main thread? How can I do that then? Thanks!

 

[jmeckley]

you have to catch the exception in the child thread. then pass this exception back to the main thread.

either create a seperate delegate/event for exceptions or include the exception as an argument/property for the completed delegate.

for example. include it with the completed event args

CompletedEventAgs : EventArgs
{
   object data;
   exception ex;
}

include the try/catch in the threaded process

try
{
  //do work
}
catch
{
   get exception
}
pass exception to completed event args (null if no error)
//call completed event

then in your parent thread check for an exception

void MyEventCompleted(object sender, CompletedEventArgs e)
{
   if(e.Exception != null)
   {
      //handle exception
   }
   else
   {
     //process completed
   }
}

or create a new object to handel exceptions.

Exception: EventArgs
{
   exception ex;
}

include the try/catch in the threaded process

try
{
  //do work
  //call completed event
}
catch
{
  //call exception event
}

then in your parent thread check for an exception

void MyEventCompleted(object sender, CompletedEventArgs e)
{
  //success
}

void MyEventErrored(object sender, ExceptionEventArgs e)
{
   //handle exception from child thread
}

Jason Meckley
Programmer
Specialty Bakers, Inc.

 

[serializer]

Thanks, but I am not getting the exact behavior I want. What I want is to throw the exception to the application that is referencing my dll.

My preferred solution would be, if possible, to create a delegate and event like this:

public delegate void DelegateThrowException(Exception ex);
public static event DelegateThrowException EventThrowException;

Then, in my main thread I add some code to the constructor:

public void New()
{
EventThrowException += new DelegateThrowException(Form1_EventThrowException);
}

void Form1_EventThrowException(Exception ex)
{
throw ex;
}

Then I would create a static method which I could call from anywhere:


public static void RaiseException(Exception ex)
{
EventThrowException(ex);
}

What is wrong with this approach?