Cross-interpreter memory leak in _xidata_release when originating interpreter is destroyed

Bug report

Bug description:

Bug report

Bug summary
There is a known memory leak in Python/crossinterp.c related to the teardown of sub-interpreters when they share data.

When a sub-interpreter packages data into _PyXIData_t and passes it to a receiving interpreter, the receiver is expected to call _PyXIData_Release to free it. However, if the originating interpreter is destroyed before the receiver calls release, the original interpreter's memory context is lost.

In _xidata_release (Python/crossinterp.c around line 1049), the code correctly identifies this state:

    PyInterpreterState *interp = _PyInterpreterState_LookUpID(
                                        _PyXIData_INTERPID(xidata));
    if (interp == NULL) {
        // The interpreter was already destroyed.
        // This function shouldn't have been called.
        // XXX Someone leaked some memory...

Because the originating interpreter is gone, Python intentionally leaks xidata->obj to avoid a use-after-free segfault.

Proposed Solution Architecture
To resolve this without crashing, we would need to track cross-interpreter data at the interpreter level:

1. Modify PyInterpreterState to include a thread-safe registry tracking all active _PyXIData_t instances created by that interpreter.
2. Register instances during _PyCode_GetXIData and deregister them during _xidata_release.
3. Modify Py_EndInterpreter teardown to check this registry. If outstanding shared data exists, the shutting-down interpreter must either block until it is released, or forcefully invalidate/free the shared data (using an is_invalidated flag) before tearing down its own obmalloc state.

I'm opening this issue to get feedback on the proposed architecture before starting a Pull Request.

CPython versions tested on:
main branch

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-153745

Bắt đầu với Python/crossinterp.c quanh _xidata_release, sau đó lần theo _PyCode_GetXIData và đường dẫn teardown của Py_EndInterpreter. Hãy xem xét công việc được liên kết gh-153745 trước khi tiếp tục, vì issue này yêu cầu phản hồi về kiến trúc và không xác định một triển khai cố định hay một bài kiểm tra hoàn tất.