The Hotspot Trap: Complexity × Churn as a Structural Signal
There is a file in the MongoDB codebase that has been touched 62 times in the last year. It is 2,273 lines long. Its cyclomatic complexity is 926 — in a codebase where the average is 53. replication_coordinator_impl.cpp Every engineer who has worked near the replication layer knows it. The name alone is enough to produce a familiar reaction: a slight tension, a quick mental calculation of whether the ticket they just picked up is going to touch it. ...