@thor, @Stefano Bonicatti, @farfella I think I located the error Stefano referenced with the shutdown refactor. It was possible to notify the condition variable used by the main thread before the main thread started waiting. An example includes starting a service thread that quickly fails (for some reason or another) that then calls requestShutdown. I changed the code such that the CV uses a predicate and a quick/early request for shutdown makes that predicate hold.