I’m not familiar with pthread_cancel, but I am with TerminateThread. It’s not something that can be used safely: ever. Raymond Chen has written a few times about it, including the history.

> Originally, there was no Terminate­Thread function. The original designers felt strongly that no such function should exist because there was no safe way to terminate a thread, and there’s no point having a function that cannot be called safely. But people screamed that they needed the Terminate­Thread function, even though it wasn’t safe, so the operating system designers caved and added the function because people demanded it. Of course, those people who insisted that they needed Terminate­Thread now regret having been given it.