## Summary
report and fix https://github.com/Comfy-Org/ComfyUI_frontend/issues/3919
- Convert recursive gcd to iterative to avoid stack overflow
- Add epsilon tolerance (1e-10) for floating-point precision issues
This fixes workflow loading hangs when node trying merge values like
0.01 and 0.001, which caused the original recursive gcd to run
indefinitely due to floating-point modulo never reaching exactly zero.
please notice, we need both iterative and epsilon together to fix this
gcd issue
Call Chain
PrimitiveNode.onAfterGraphConfigured
→ #mergeWidgetConfig
→ #isValidConnection
→ mergeIfValid
→ mergeInputSpec
→ mergeNumericInputSpec
→ lcm(step1, step2)
→ gcd(a, b) ← Problem here
Why It Happened
When some nodes connect to multiple nodes, it may merge values using
LCM, which internally calls GCD.
Original recursive implementation:
```
export const gcd = (a: number, b: number): number => {
return b === 0 ? a : gcd(b, a % b)
}
```
Issues:
1. Stack Overflow: Recursive calls with many nodes exhausted the call
stack.
2. Floating-Point Precision: For values like gcd(0.01, 0.001):
` 0.01 % 0.001 = 0.0009999999999999994 // Not exactly 0!`
3. Due to Ifloating-point representation, the modulo never reaches
exactly zero, causing hundreds or thousands of iterations.
## Screenshots
### before
https://github.com/user-attachments/assets/cca4342c-a882-4590-a8d4-1e0bea19e5b7
### fix with only iterative, without epsilon
https://github.com/user-attachments/assets/1dc52aa4-a86a-40b5-8bac-904094c4c36b
### final fix with iterative and epsilon
https://github.com/user-attachments/assets/7b868b50-c3c9-4be4-8594-27cecbc08a26
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7258-performance-fix-prevent-gcd-infinite-loop-with-floating-point-step-values-2c46d73d3650818cbe8cf455c934a114)
by [Unito](https://www.unito.io)
