Characterizing logging practices in Java-based open source software projects – a replication study in Apache Software Foundation

Log messages, which are generated by the debug statements that developers insert into the code at runtime, contain rich information about the runtime behavior of software systems. Log messages are used widely for system monitoring, problem diagnoses and legal compliances. Yuan et al. performed the first empirical study on the logging practices in open source software systems. They studied the development history of four C/C++ server-side projects and derived ten interesting findings. In this paper, we have performed a replication study in order to assess whether their findings would be applicable to Java projects in Apache Software Foundations. We examined 21 different Java-based open source projects from three different categories: server-side, client-side and supporting-component. Similar to the original study, our results show that all projects contain logging code, which is actively maintained. However, contrary to the original study, bug reports containing log messages take a longer time to resolve than bug reports without log messages. A significantly higher portion of log updates are for enhancing the quality of logs (e.g., formatting & style changes and spelling/grammar fixes) rather than co-changes with feature implementations (e.g., updating variable names).