To calculate the truck factor, we use a greedy heuristic: we consecutively remove the author with more authored files in a system, until more than 50% of the system’s files are orphans (i.e., without author). We are considering that a system is in trouble if more than 50% of its files are orphans.
He calculated the Truck Factor on 133 popular GitHub repositories in six languages.
Our results are summarized as follows:
- Most systems have a small truck factor:
- 61 systems have TF=1 (46%), including systems like mbostock/d3, and clojure/clojure.
- 37 systems have TF=2 (28%), including systems like cucumber/cucumber, mrdoob/three.js, mozilla/pdf.js, spring-projects/spring-framework.
- The two systems with the highest Truck Factor are torvalds/linux (TF = 90) and Homebrew/homebrew (TF = 159).