An empirical analysis of the FixCache algorithm

Abstract

The FixCache algorithm, introduced in 2007, effectively identifies files or methods which are likely to contain bugs by analyzing source control repository history. However, many open questions remain about the behaviour of this algorithm. What is the variation in the hit rate over time? How long do files stay in the cache? Do buggy files tend to stay buggy, or can they be redeemed? This paper analyzes the behaviour of the FixCache algorithm on four open source projects. FixCache hit rate is found to generally increase over time for three of the four projects; file duration in cache follows a Zipf distribution; and topmost bug-fixed files go through periods of greater and lesser stability over a project's history.