Parallel changes in large-scale software development: An observational case study

Am essential characteristic of large-scale software development is parallel development by teams of developers. How this parallel development is struc tured and supported has a profound effect on both the quality and timelines s of the product. We conduct an observational case study in which we collec t and analyze the change and configuration management history of a legacy s ystem to delineate the boundaries of, and to understand the nature of, the problems encountered in parallel development. The results of our studies ar e (1) that the degree of parallelism is very high-higher than considered by tool builders; (2) there are multiple levels of parallelism, and the data for some important aspects are uniform and consistent for all levels; (3) t he tails of the distributions are long, indicating the tail, rather than th e mean, must receive serious attention in providing solutions for these pro blems; and (4) there is a significant correlation between the degree of par allel work on a given component and the number of quality problems it has. Thus, the results of this study are important both for tool builders and fo r process and project engineers.