Do Not Allow Static Objects to be Deallocated

The runtime currently has many objects that are statically defined. See Include/internal/pycore_global_objects.h. For the singletons, all instances of the type are statically defined. Otherwise only some instances are.

The problem is that if tp_dealloc() for one of the affected types tries to free a static object then it will crash. We've set the refcount for such objects to a really high number to avoid this, but it is still possible. The risk rises a bit for immortal objects (see PEP 683).

For all types with static objects, we need to add a check in tp_dealloc() to either fail or reset the refcount to the really high number. We already have a check like this for the singletons and for str. For the other types we need to identify if the object is static and respond accordingly. The catch is that identifying that can be expensive, which is problematic for types that are deallocated frequently.

まず Include/internal/pycore_global_objects.h から始めて静的に定義されたオブジェクトを一覧化し、次に影響を受ける型の tp_dealloc 実装を調べます。許容できないデアロケーションオーバーヘッドなしに各型が静的オブジェクトを識別する方法を決定します。静的オブジェクトを解放できず、refcount 関連のクラッシュも引き起こさない状態になれば完了です。