Interactive, Effort-Aware Library Version Harmonization

As a mixed result of intensive dependency on third-party libraries, flexible mechanisms to declare dependencies and increased number of modules in a project, different modules of a project directly depend on multiple versions of the same third-party library. Such library version inconsistencies could increase dependency maintenance cost, or even lead to dependency conflicts when modules are inter-dependent. Although automated build tools (e.g., Maven's enforcer plugin) provide partial support to detect library version inconsistencies, they do not provide any support to harmonize inconsistent library versions. We first conduct a survey with 131 Java developers from GitHub to retrieve first-hand information about the root causes, detection methods, reasons for fixing or not fixing, fixing strategies, fixing efforts, and tool expectations on library version inconsistencies. Then, based on the insights from our survey, we propose LibHarmo, an interactive, effort-aware library version harmonization technique, to detect library version inconsistencies, interactively suggest a harmonized version with the least harmonization efforts based on library API usage analysis, and refactor build configuration files. LibHarmo is currently developed for Java Maven projects. Our experimental study on 443 highly-starred Java Maven projects from GitHub shows that i) LibHarmo detected 621 library version inconsistencies in 152 (34.3%) projects with a false positive rate of 16.8%, while Maven's enforcer plugin only detected 219 of them; and ii) LibHarmo saved 87.5% of the harmonization efforts. Further, 31 library version inconsistencies have been confirmed, and 17 of them have been already harmonized by developers.