[Side A] Completely Defending Python from OOM Kills: The BytesIO Trap and D-MemFS 'Hard Quota' Design Philosophy

From the Author: Recently, I introduced D-MemFS on Reddit. The response was overwhelming, confirming that memory management and file I/O performance are truly universal challenges for developers everywhere. This series is my response to that global interest. 🧭 About this Series: The Two Sides of Development To provide a complete picture of this project, I’ve split each update into two perspectives: Side A (Practical / from Qiita): Implementation details, benchmarks, and technical solutions. Side B (Philosophy / from Zenn): The development war stories, AI-collaboration, and design decisions. Introduction If you write in-memory processing in Python, you will eventually encounter this kind of failure: Killed Or on Windows, the process simply vanishes without a word. It's an OOM (Out of Memory) kill. Both io.BytesIO and dict will expand limitlessly until memory runs out. The process disappears without you even knowing "where" or "why" it crashed—this is one of the most troublesome pitfall