Py314t uses 2× memory

I’m migrating BEVFormer (an auto-driving model training framework) from Py3.14 to 3.14t. Functionally it runs, but memory usage (RAM, not GPU memory) on 3.14t is about twice that of 3.14. I’ve run many training epochs and tried different GPUs; the issue reproduces reliably. I traced it to BRC (biased ref count): when a non-owner thread decrefs and ob_ref_shared comes to 0, it has to have the owner thread read ob_ref_local and confirm the object can be collected. If the owner is detached, collec...