Finding the Root Cause of Mystical Problems - The Bisection Debugging Method

This article proposes a general problem-solving strategy called the "Squeeze Debugging Method," designed to rapidly identify technical failures that behave normally in ideal environments but exhibit anomalies in specific ones. The core logic of this method involves constructing an ideal environment E2 that guarantees normal program execution and comparing it with the actual environment E1 where the anomaly occurs, thereby identifying the set of differences between the two. Subsequently, through a bidirectional approach, the characteristics of the ideal environment are incrementally applied to the faulty environment, or vice versa, while observing whether the anomalous behavior changes, thus narrowing down the range of potential causes. The article emphasizes that this method is particularly effective for "mystical" issues that are difficult to resolve through conventional search methods. Its objective is to identify "potential conditions" that may contribute to the problem, rather than establishing strict necessary and sufficient conditions. Through two case studies—Spotify failing to run and an aircraft engine startup failure—the article demonstrates how to execute this debugging process in practice. It highlights that this method efficiently helps developers or users quickly identify key influencing factors from complex environmental variables, enabling them to independently resolve difficult-to-reproduce or pinpoint anomalies.