Directly check if/which interpreter is active before doing CLEAR in destructors.

Py_IsFinalizing only applies to the main interpreter.

Author: b-pass

include/pybind11/detail/internals.h

@@ -143,6 +143,16 @@ inline PyTypeObject *make_default_metaclass();
 inline PyObject *make_object_base_type(PyTypeObject *metaclass);
 inline void translate_exception(std::exception_ptr p);
 
+inline PyThreadState *get_thread_state_unchecked() {
+#if defined(PYPY_VERSION) || defined(GRAALVM_PYTHON)
+    return PyThreadState_GET();
+#elif PY_VERSION_HEX < 0x030D0000
+    return _PyThreadState_UncheckedGet();
+#else
+    return PyThreadState_GetUnchecked();
+#endif
+}
+
 // Python loads modules by default with dlopen with the RTLD_LOCAL flag; under libc++ and possibly
 // other STLs, this means `typeid(A)` from one module won't equal `typeid(A)` from another module
 // even when `A` is the same, non-hidden-visibility type (e.g. from a common include).  Under
@@ -195,14 +205,6 @@ struct override_hash {
 
 using instance_map = std::unordered_multimap<const void *, instance *>;
 
-inline bool is_interpreter_alive() {
-#if PY_VERSION_HEX < 0x030D0000
-    return Py_IsInitialized() != 0 || _Py_IsFinalizing() != 0;
-#else
-    return Py_IsInitialized() != 0 || Py_IsFinalizing() != 0;
-#endif
-}
-
 #ifdef Py_GIL_DISABLED
 // Wrapper around PyMutex to provide BasicLockable semantics
 class pymutex {
@@ -295,9 +297,7 @@ struct internals {
         : static_property_type(make_static_property_type()),
           default_metaclass(make_default_metaclass()) {
         tstate.set(nullptr); // See PR #5870
-        PyThreadState *cur_tstate = PyThreadState_Get();
-
-        istate = cur_tstate->interp;
+        istate = PyInterpreterState_Get();
         registered_exception_translators.push_front(&translate_exception);
 #ifdef Py_GIL_DISABLED
         // Scale proportional to the number of cores. 2x is a heuristic to reduce contention.
@@ -320,8 +320,10 @@ struct internals {
         // Normally this destructor runs during interpreter finalization and it may DECREF things.
         // In odd finalization scenarios it might end up running after the interpreter has
         // completely shut down, In that case, we should not decref these objects because pymalloc
-        // is gone.
-        if (is_interpreter_alive()) {
+        // is gone.  This also applies across sub-interpreters, we should only DECREF when the
+        // original owning interpreter is active.
+        auto *tstate = get_thread_state_unchecked();
+        if (tstate && tstate->interp == istate) {
             Py_CLEAR(instance_base);
             Py_CLEAR(default_metaclass);
             Py_CLEAR(static_property_type);
@@ -336,20 +338,25 @@ struct internals {
 // impact any other modules, because the only things accessing the local internals is the
 // module that contains them.
 struct local_internals {
+    local_internals() : istate(PyInterpreterState_Get()) {}
+
     // It should be safe to use fast_type_map here because this entire
     // data structure is scoped to our single module, and thus a single
     // DSO and single instance of type_info for any particular type.
     fast_type_map<type_info *> registered_types_cpp;
 
     std::forward_list<ExceptionTranslator> registered_exception_translators;
     PyTypeObject *function_record_py_type = nullptr;
+    PyInterpreterState *istate = nullptr;
 
     ~local_internals() {
         // Normally this destructor runs during interpreter finalization and it may DECREF things.
         // In odd finalization scenarios it might end up running after the interpreter has
         // completely shut down, In that case, we should not decref these objects because pymalloc
-        // is gone.
-        if (is_interpreter_alive()) {
+        // is gone.  This also applies across sub-interpreters, we should only DECREF when the
+        // original owning interpreter is active.
+        auto *tstate = get_thread_state_unchecked();
+        if (tstate && tstate->interp == istate) {
             Py_CLEAR(function_record_py_type);
         }
     }
@@ -436,16 +443,6 @@ struct native_enum_record {
     "__pybind11_module_local_v" PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION)                     \
         PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE PYBIND11_PLATFORM_ABI_ID "__"
 
-inline PyThreadState *get_thread_state_unchecked() {
-#if defined(PYPY_VERSION) || defined(GRAALVM_PYTHON)
-    return PyThreadState_GET();
-#elif PY_VERSION_HEX < 0x030D0000
-    return _PyThreadState_UncheckedGet();
-#else
-    return PyThreadState_GetUnchecked();
-#endif
-}
-
 /// We use this to figure out if there are or have been multiple subinterpreters active at any
 /// point. This must never go from true to false while any interpreter may be running in any
 /// thread!