Messages for exceptions only for main thread?

[Cristian Peța 103]

I just realized that exception messages are shown only for main thread. I'm right? And if yes, why?

 

madExcept will show exception for all app threads and I was surprised to see that without madExcept you can see exceptions for other threads only debugging from IDE.

[Uwe Raabe 2057]

It is probably related to this code in System.Classes.ThreadProc:

    try
      Thread.Execute;
    except
      Thread.FFatalException := AcquireExceptionObject;
    end;

You should be able to get any exception in the threads OnTerminate handler reading its FatalException property. See also http://docwiki.embarcadero.com/Libraries/Rio/en/System.Classes.TThread.FatalException

[David Heffernan 2345]

All UI happens from the UI thread. So if you want an exception from another thread to result in UI, you need to marshal it into the main thread.

 

Having madExcept in your process is great. But there are a class of exceptions that you don't want to trouble the user with a bug report. I call these expected exceptions. You need to decide on a policy for those exceptions. 

[Hafedh TRIMECHE 1]

You may try this code:

procedure GlobalExceptionHandler(ExceptionObj:TObject);
var
  LException : Exception;
begin
  if (ExceptionObj is Exception) then LException := Exception(ExceptionObj)
                                 else LException := nil;
  TExceptionHandler.ProcessException(nil,LException);
end;

constructor TExceptionHandler.Create;
begin
  inherited;
  JclStackTrackingOptions := [stStack,stRawMode,stTraceAllExceptions];
  JclStartExceptionTracking;
  Application.OnException  := ProcessException;
  ExceptionAcquired        := @GlobalExceptionHandler;
end;

destructor TExceptionHandler.Destroy;
begin
  StopExceptionHandler;
  inherited;
end;

It worked for me !