Why does the order of elements in python's set object change when program is ran more than once

Question

I have this set and when I run this program twice the order of printing is changed

S = {7, "veil", 0, -29, ("x", 11), "sun", frozenset({8, 4, 7}), 913}
print(S)

first time output:- {'veil', 0, -29, 'sun', 7, frozenset({8, 4, 7}), ('x', 11), 913}

second time output:- {0, -29, 7, frozenset({8, 4, 7}), 'veil', 913, ('x', 11), 'sun'}

I assumed that this behaviour is because only hashable objects can be added to a set and it is unordered but since a dictionary's keys are hashable and it is unordered then a dictionary should show this behaviour too, but it doesn't

Why does the order of the elements change in the set?

A set is an unsorted list of items; so I would think the order of elements is not defined (and thus random); — Oliver Mason, Apr 24 '20 at 16:03
@OliverMason why does the dictionary shows a different behaviour? — Neminda Prabhashwara, Apr 24 '20 at 16:11
It is a direct implication of a securtiy patch explained here https://stackoverflow.com/a/27522708/5378816 — VPfB, Apr 24 '20 at 16:13
@RoadRunner but dictionaries are unordered , they don't show this behaviour — Neminda Prabhashwara, Apr 24 '20 at 16:16
@VPfB Is correct, this is due to hash randomization (as explained in the linked duplicate). — wim, Apr 24 '20 at 16:17
@wim I read those answers and set problem is clear for me now, but since dictionarie's keys also `hashabale` but its items always shows in the order that they were added. Why does that happen? — Neminda Prabhashwara, Apr 24 '20 at 16:39
The implementation of sets and dicts is entirely different. Dicts preserve insertion order. — wim, Apr 24 '20 at 16:48
@wim as explained in here [https://stackoverflow.com/a/27522708/5378816](https://stackoverflow.com/a/27522708/5378816) it syas that random hashing can affect of dicts — Neminda Prabhashwara, Apr 24 '20 at 17:00
@VPfB as you pointed in your link it says that dicts' order is affected by random hashing, but it doen't — Neminda Prabhashwara, Apr 24 '20 at 17:04
@NemindaPrabhashwara You're right. Martijn's answer is from 2014, it's now outdated/incorrect. The dicts preserving ordering was added to the language in 2018. — wim, Apr 24 '20 at 17:05
Thanks to everybody adding details and corrections. I did not pay attention to the dict part. — VPfB, Apr 24 '20 at 17:37
@NemindaPrabhashwara: I've updated my answer; what changed is that the implementation of `dict` was updated in Python 3.6 to be more more memory efficient. A side-effect of this change is that the `dict` type now lists keys in insertion order, irrespective of the hash value. This same change can't be applied to sets, however. — Martijn Pieters, Apr 26 '20 at 12:17
@MartijnPieters It is an excellent answer thanks for the update. — Neminda Prabhashwara, Apr 26 '20 at 13:55

Why does the order of elements in python's set object change when program is ran more than once

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