Truck Factor

July 13, 2015 opensource , commentary 1 min read

@mtov posts on the “Truck Factor“—the minimal number of developers that have to be hit by a truck before a project is incapacitated—of open source projects on GitHub.

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).
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avatar of Brandon Keepers I am Brandon Keepers, and I work at GitHub on making Open Source more approachable, effective, and ubiquitous. I tend to think like an engineer, work like an artist, dream like an astronaut, love like a human, and sleep like a baby.