An empirical study of long lived bugs

Bug fixing is a crucial part of software development and maintenance. A large number of bugs often indicate poor software quality since buggy behavior not only causes failures that may be costly but also has a detrimental effect on the user's overall experience with the software product. The impact of long lived bugs can be even more critical since experiencing the same bug version after version can be particularly frustrating for user. While there are many studies that investigate factors affecting bug fixing time for entire bug repositories, to the best of our knowledge, none of these studies investigates the extent and reasons of long lived bugs. In this paper, we analyzed long lived bugs from five different perspectives: their proportion, severity, assignment, reasons, as well as the nature of fixes. Our study on four open-source projects shows that there are a considerable number of long lived bugs in each system and over 90% of them adversely affect the user's experience. The reasons of these long lived bugs are diverse including long assignment time, not understanding their importance in advance etc. However, many bug-fixes were delayed without any specific reasons. Our analysis of bug fixing changes further shows that many long lived bugs can be fixed quickly through careful prioritization. We believe our results will help both developers and researchers to better understand factors behind delays, improve the overall bug fixing process, and investigate analytical approaches for prioritizing bugs based on bug severity as well as expected bug fixing effort.