How to debug a deadlock?

I'd try different approaches in the following order:

• First, inspect the code to look for thread-safety violations, making sure that your critical regions don't call other functions that will in turn try to lock a critical region.

• Use whatever tool you can get your hands on to visualize thread activity, I use an in-house perl script that parses an OS log we made and graphs all the context switches and shows when a thread gets pre-empted.

• If you can't find a good tool, do some logging to see the last threads that were running before the deadlock occurred. This will give you a clue as to where the issue might be caused, it helps if the locking mechanisms have unique names, like if an object has it's own thread, create a dedicated semaphore or mutex just to manage that thread.

I hope this helps. Good luck!

What you did was the correct way. If Visual Studio also deadlocks, that happens now and then. It's just bad luck, unless there's some other issue.

You don't have to run the application in the debugger in order to debug it. Run the application normally, and if the deadlock happens, you can attach VS later. Ctrl+Alt+P, select the process, choose debugger type and click attach. Using a different set of debugger types might reduce the risk of VS crashing (especially if you don't debug native code)

A deadlock involves 2 or more threads. You probably know the first one (probably your UI thread) since you noticed the deadlock in your application. Now you only need to find the other one. With knowledge of the architecture, it should be easy to find (e.g. what other threads use the same locks, interact with the UI etc)

If VS doesn't work at all, you can always use windbg. Download here: http://www.microsoft.com/whdc/devtools/debugging/default.mspx