By Eric Raymond
Linus' Law as described by Raymond is a claim about software development, named in honor of Linus Torvalds and formulated by Raymond in his essay and book "The Cathedral and the Bazaar" (1999). The law states that "given enough eyeballs, all bugs are shallow"; or more formally: "Given a large enough beta-tester and co-developer base, almost every problem will be characterized quickly and the fix will be obvious to someone." Presenting the code to multiple developers with the purpose of reaching consensus about its acceptance is a simple form of software reviewing. Researchers and practitioners have repeatedly shown the effectiveness of various types of reviewing process in finding bugs and security issues, and also that reviews may be more efficient than testing.
In Facts and Fallacies about Software Engineering, Robert Glass refers to Linus' Law as a "mantra" of the Open source movement, but calls it a fallacy, stating that research has found that the number of bugs found decreases with too many inspectors, and that no research supports the Law as stated. While closed-source practitioners also promote stringent, independent code analysis during a software project's development, they focus on in-depth review by a few and not primarily the number of "eyeballs".
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