Sockets, multithreading, and not seeing Exceptions

Hello folks, I'm working on writing a multiplayer api to communicate with my game server. I'm noticing an issue with exceptions not being displayed in Unity when inside an AsyncCallback function.

So for example the below error will not be displayed in Unity at all, so I'll have a tough time knowing something went wrong.

Code (CSharp):

1.  
2. Socket clientSocket = new Socket(......);
3. clientSocket.BeginConnect(IPAddress.Loopback, 8184, onConnected, clientSocket);
4.  
5. void onConnected(IAsyncResult _result){
6.      print("Can you see me?"); //Will be displayed.
7.      throw new Exception("testing"); //Will NOT be displayed in Unity.
8. }
9.  

Any idea why this is, or how I can fix it? I'm not super familiar with multithreading in Unity just yet. I've used it in .Net applications a bit, but not in Unity. From what I read, Unity is not multithread friendly in some aspects. Could this have to do why I'm not seeing the errors? Additionally, is it safe to manipulate game objects inside of ASyncCallbacks for messages from the server? Or do I need to go about that a different way?

 

So after some digging, it appears that exceptions just aren't displayed when raised from threads that aren't the main thread. I guess that's just how it is. Looks like I have to wrap more sensitive code in a try/catch and manually print to the console window. A little ugly, but I guess it'll do.

My same question still stands regarding modifying game objects in the asynccallback for incoming socket data. I imagine that is not thread safe then? If so, what would be the best approach? To queue the data in some thread safe collection and execute the message in an Update function?

 

You could wrap your whole thread function try/catch(Exception) to catch anything that might happen in there. Then use Debug.LogError to log it.

 

I thought such errors getting caught in other threads was added to Unity in 2018.3. Maybe I read the release notes wrong.

 

I wasn't aware of that. Perhaps they do get caught now.

 

AppDomain.CurrentDomain.UnhandledException += (sender, e) => Debug.LogError(e.ExceptionObject);

 

Thanks for the suggestion. I currently wrapped them in try/catch, I'll have to give the AppDomain suggestion a try and see if it works.

 

Just reporting back. The AppDomain.CurrentDomain.UnhandledException recommendation is not appearing to work. So wrapping all multithreaded code int a try/catch is still the only viable solution.

 

Generally speaking it's also the most sensible one.