List live objects of certain type in current Python interpreter.

list_live_objects.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import gc


def list_live_objects(ty=None):
    def go(results, elements, bitset):
        for elem in elements:
            identity = id(elem)
            if identity in bitset:
                continue
            bitset.add(identity)
            if ty is None or isinstance(elem, ty):
                results.append(elem)
            referents = gc.get_referents(elem)
            if referents:
                go(results, referents, bitset)
    
    elements = gc.get_objects()
    results = []
    bitset = set()
    go(results, elements, bitset)
    return results

################ examples ###############################

def list_objects():
    return list_live_objects()

def list_lists():
    return list_live_objects(list)

def list_ndarrays():
    import numpy
    return list_live_objects(numpy.ndarray)