Event problem with VS 2005

microsoft.public.dotnet.framework

27 Sep 2006 12:56 AM

Roger Crawfis

We upgraded our volume renderer to 2005, but it crashes with our event
system when using the OneWay attribute. We get a null exception as
outlined below in a ListDictionary with a count of zero. This is not our
data structure, but appears to be the ThreadPool classes instance. Of course
for OneWay, we do not want a WaitCallback, so I am suspect to see the call
stack below. Can anyone help with this? IDid something change in VS 2005
with
the OneWay attribute? We are using Visual Team Studio 2005 Professional.

System.NullReferenceException was unhandled
Message="Object reference not set to an instance of an object."
Source="mscorlib"
StackTrace:
       at
System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMess
age msg, IMessageSink replySink)
       at
System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.ThreadPoolCallBack(Obje
ct o)
       at
System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext
executionContext, ContextCallback callback, Object state)
       at
System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

A little more on the situation:
- The event creates (uses) a new thread from the thread pool and executes
the delegate. The delegate may need to modify a control. If so, it marshals
it over to the UI thread. The UI thread executes fine and processes the
request. When it returns, the event delegate thread seems to crash. Changing
to Serial or Async event handling works fine. I have enclosed the
EventHelper class that we use. Only the OneWay causes problems. Switching it
to
Serial of Asynchronous works fine.

I can provide the entire project for a simple test program.

Roger

[attached file: EventsHelper.cs]