Python FTW: Under the Hood/

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Bloating Instance dicts

Bloating Instance dicts

We'll cover the following...

Bloating is painful in-person and in Python.

⚠️ The following codes are meant for Python 3.8. Other Python 3 versions may vary a little.

C++
import sys
class SomeClass:
    def __init__(self):
        self.some_attr1 = 1
        self.some_attr2 = 2
        self.some_attr3 = 3
        self.some_attr4 = 4
def dict_size(o):
    print(sys.getsizeof(o.__dict__))
o1 = SomeClass()
o2 = SomeClass()
dict_size(o1)
dict_size(o2)
del o1.some_attr1
o3 = SomeClass()
dict_size(o3)
dict_size(o1)

Let’s try again…in a new code widget:

C++
import sys
class SomeClass:
    def __init__(self):
        self.some_attr1 = 1
        self.some_attr2 = 2
        self.some_attr3 = 3
        self.some_attr4 = 4
def dict_size(o):
    print(sys.getsizeof(o.__dict__))
o1 = SomeClass()
o2 = SomeClass()
dict_size(o1)
o1.some_attr5 = 5
o1.some_attr6 = 6
dict_size(o1) # as expected
dict_size(o2)
o3 = SomeClass()
dict_size(o3)

What makes those dictionaries become bloated? And why are newly created objects bloated as well?

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