Resolving the software maintenance paradox
Bruce I. Blum · Journal of Software Maintenance Research and Practice · 1995
Abstract This paper explores the apparent paradox that, although performance improves with experience, the maintenance of a software system becomes more difficult as experience with it accumulates. It is asserted that this phenomenon is a side effect of the environment used to maintain the software. A decade of experience with a large and complex clinical information system is summarized to demonstrate that software maintenance may be inherently less difficult than original development. It is shown that a highly integrated, million‐line, operational system, used in life‐threatening situations, has been maintained effectively by a staff of six. During the past five years, the size of the system increased by 167%. In addition to maintaining a growing number of programs, the staff produced new programs at a rate of 0.64 programs per effort‐day. Moreover, the case study also demonstrates that this level of performance can be transported to other sites. The paper concludes with some observations regarding changes to the software process that will resolve the paradox.