Python. I have been watching the PTVSD development very closely since 5.0 aims to address most of the problems I have. They just got spawn and fork support in recently so things should be much better now but it’s still pre-release and there’s a number of open issues left to solve. I didn’t have to work on threaded code in PHP so it may not have been fair to bring that up at all since it’s mostly irrelevant to the point that it was very easy to setup PHP debugging for my use cases and it was slightly more work to setup Python initially.

The improvements in the new version of ptvsd are around multi-process debugging, though, not so much multithreading, hence why I was curious. Multithreading was supported before VSCode even, going all the way back to PTVS 1.0, so if we still have any major issues with that, I'd definitely like to know!