EVE Online begins 16-year Python upgrade, 2.4 million lines of code
Simon Willison
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Originally published as “EVE Online: The Move to Python 3 Begins!”
Highlights
- EVE Online migrating 2.4M lines of code from Python 2.7 to Python 3
- Manual review required for ~20,000 Python 2/3 behavioral differences
- Stackless Python replacement strategy already proven in EVE Frontier
- Sixteen-year gap since last major Python upgrade
EVE Online, which has run on Stackless Python since 2003, is beginning its migration to Python 3 after 16 years on Python 2.7. The upgrade will apply automated tooling (futurize) to 2.4 million lines of code, followed by manual review of approximately 20,000 locations where Python 2 and 3 behavior diverges—such as integer division semantics. This represents a significant infrastructure undertaking for one of gaming's longest-running Python deployments. The announcement does not detail how EVE Online will replace Stackless Python itself, though the company has previously demonstrated a replacement approach (carbonengine/scheduler, now open source) used in their newer title EVE Frontier. This migration is relevant to anyone managing large legacy Python codebases or interested in how production systems at scale handle language version transitions.
