How to debug thread code

[Hipreme via Digitalmars-d-learn]

I'm stuck in a racing condition right now and I'm unable to run a 
debugger on the code. Usually I was using Visual Studio 2019 for 
debugging my code, but it shows the following message:

"Your app has entered a break state, but there is no code to show 
because all threads were executing external code (typically 
system or framework code)."

I can only access the main thread code which stops on my semaphore