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.

从 Include/internal/pycore_global_objects.h 开始，盘点静态定义的对象，然后检查受影响类型的 tp_dealloc 实现。确定每种类型如何在不产生不可接受的释放开销的情况下识别静态对象；完成的标准是静态对象无法被释放，也不会导致与 refcount 相关的崩溃。