Practices of software maintenance

This paper describes the results of an interview study conducted at ten industrial sites. The interview focused on the work practices of software engineers engaged in maintaining large scale systems. Five 'truths' emerged from this study. First, software maintenance engineers are experts in the systems they are maintaining. Second, source code is the primary source of information about systems. Third, the documentation is used, but not necessarily trusted. Fourth, maintenance control systems are important repositories of information about systems. Finally, reproduction of problems and/or problem scenarios is essential to problem solutions. These truths confirm much of the conventional wisdom in the field. However, in fleshing them out, details were elaborated, and additionally new knowledge was acquired. These results are discussed with respect to tool design.