CODEWITHSUNDEEP
python
symon
symon

Reputation: 650

why is a dict size 72 bytes after calling .clear() compared to 240 bytes when instantiating one?

What is happening under the hood to have a dict size of 72 bytes (according to getsizeof(dict) after calling .clear() on the dictionary, when a freshly instantiated one returns 240 bytes?

I know a simple dict has a starting size of '8' and resizes itself upon ~66% fullness, is this relatable to the size after calling clear?

I am studying dictionaries and found this quite interesting, what is actually happening?

>>> from sys import getsizeof
>>> dict = {}
>>> getsizeof(dict)
240
>>> dict.clear()
>>> getsizeof(dict)
72
>>>

Upvotes: 2

Views: 98

Answers (1)

user2722968
user2722968

Reputation: 16485

Assuming we are talking CPython, your intuition is correct. When creating a new dictionary, a keyspace is allocated in dict_new of size PyDict_MINSIZE. This consumes memory. When calling .clear(), the keyspace is re-wired to a statically allocated empty key-space, making the dictionary truly empty.

Upvotes: 2

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