Python Dictionaries

> Python then calculates the hash value for each key in the dictionary using the MurmurHash3 hash function.

Umm... this isn't right. At all. Depending on configuration, Python uses an external hash, a Modified Fowler-Noll-Vo (FNV) hash, or SipHash.

Here's a quote from Include/pyhash.h :

* The values for Py_HASH_* are hard-coded in the * configure script. * * - FNV and SIPHASH* are available on all platforms and architectures. * - With EXTERNAL embedders can provide an alternative implementation with::

and the implementations are in Python/pyhash.c .

The only "murmur" in the repo is in Tools/peg_generator/data/top-pypi-packages-365-days.json as a mention of a PyPI modules.

And the linked-to Wikipedia page at https://en.wikipedia.org/wiki/MurmurHash says: "The authors of the attack recommend to use their own SipHash instead" to avoid collision attacks.

(Also, the example hash is 5478795832145536229 which is a 64-bit hash, while the Wikipedia page says MurmurHash3 generates a 32-bit or 128-bit hash value.)

> When a hash collision occurs, Python stores multiple key-value pairs in the same bucket and uses a linked list to store them.

Umm ... that isn't right either.

A linked list is an "open hashing"/"separate chaining" hash table, but Python uses "closed hashing"/"open addressing." As the linked-to Python source explains, "Open addressing is preferred over chaining since the link overhead for chaining would be substantial (100% with typical malloc overhead)."

skilled's comment about this being ChatGPT generated is flagged and dead, but ChatGPT seems good at being both wrong and confident. Just like this essay.