[nas]

The key enabling tech is thread safe reference counting. There are many other problems that Sam Gross solved in order to make it happen but the reference counting was one of the major blockers.

[the5avage]

Is this implemented with lockless programming? Is it a reason for the performance drop in single thread code?

Does it eliminate the need for a GC pause completely?

[nas]

You should probably just read the PEP, which explains these things:

https://peps.python.org/pep-0703/#reference-counting

If by GC you mean the cyclic GC, free-threaded Python currently stops all threads while the cyclic GC is running.

[the5avage]

Thank you:)