…rpreters (pythongh-102925)This is effectively two changes.  The first (the bulk of the change) is where we add _Py_AddToGlobalDict() (and _PyRuntime.cached_objects.main_tstate, etc.).  The second (much smaller) change is where we update PyUnicode_InternInPlace() to use _Py_AddToGlobalDict() instead of calling PyDict_SetDefault() directly.Basically, _Py_AddToGlobalDict() is a wrapper around PyDict_SetDefault() that should be used whenever we need to add a value to a runtime-global dict object (in the few cases where we are leaving the container global rather than moving it to PyInterpreterState, e.g. the interned strings dict).  _Py_AddToGlobalDict() does all the necessary work to make sure the target global dict is shared safely between isolated interpreters.  This is especially important as we move the obmalloc state to each interpreter (pythongh-101660), as well as, potentially, the GIL (PEP 684).python#100227

…ted Interpreters (pythongh-102925)"This reverts commit87be8d9.

… Safe for Isolated Interpreters" (gh-103063)This reverts commit 87be8d9.This approach to keeping the interned strings safe is turning out to be too complex for my taste (due to obmalloc isolation). For now I'm going with the simpler solution, making the dict per-interpreter. We can revisit that later if we want a sharing solution.

…rpreters (pythongh-102925)This is effectively two changes.  The first (the bulk of the change) is where we add _Py_AddToGlobalDict() (and _PyRuntime.cached_objects.main_tstate, etc.).  The second (much smaller) change is where we update PyUnicode_InternInPlace() to use _Py_AddToGlobalDict() instead of calling PyDict_SetDefault() directly.Basically, _Py_AddToGlobalDict() is a wrapper around PyDict_SetDefault() that should be used whenever we need to add a value to a runtime-global dict object (in the few cases where we are leaving the container global rather than moving it to PyInterpreterState, e.g. the interned strings dict).  _Py_AddToGlobalDict() does all the necessary work to make sure the target global dict is shared safely between isolated interpreters.  This is especially important as we move the obmalloc state to each interpreter (pythongh-101660), as well as, potentially, the GIL (PEP 684).python#100227

…obal Interned Dict Safe for Isolated Interpreters" (pythongh-103063)This reverts commit 87be8d9.This approach to keeping the interned strings safe is turning out to be too complex for my taste (due to obmalloc isolation). For now I'm going with the simpler solution, making the dict per-interpreter. We can revisit that later if we want a sharing solution.