How Python manages memory. Every Python object has a reference count, also known as a refcount.The refcount is a tally of the total number of other objects that hold a reference to a given object.

Python objects are “reference counted.” This means that whenever an object is assigned a new name ... When an object’s reference count reaches 0 it is “garbage collected” ...

PEP 683 allows objects to be treated as “immortal,” so that they never have their reference count changed. Making objects immortal has other powerful implications for Python in the long run.

It is possible to test numpy reference counts using pytest-leaks which as of now (July 2019) runs mostly clean through with NumPy. To do this you need to: Have a python debug build available (I use ...