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Parallel Changes in Large-Scale Software Development: An Observational Case Study DEWAYNE E. PERRY University of Texas at Austin HARVEY P. SIY Lucent Technologies and LAWRENCE G. VOTTA Motorola, Inc. Greg Holifield. Four Essential Problems in Software Development: [Brooks 1987]. Evolution
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Parallel Changes in Large-Scale SoftwareDevelopment: An Observational CaseStudyDEWAYNE E. PERRYUniversity of Texas at AustinHARVEY P. SIYLucent TechnologiesandLAWRENCE G. VOTTAMotorola, Inc. Greg Holifield
Four Essential Problems in Software Development: [Brooks 1987] • Evolution • not only have parallel development within each release, • Among releases as well. • Scale • Multiple dimensions of system organization 1[Perry 1996] • Distribution of knowledge
Authors’ Three Goals • provide a basic understanding of the parallel-change phenomena • begin an investigation of a subproblem: interfering changes • explore the relationship between parallel changes and the related quality data
Methods Toward Each Goal • basic observational data on the nature of parallel changes • Examine prima facie cases • changes to changes • changes within the same day • summarize available tools that support parallel development
Classical Tools • Library-type Systems (check in/out) • SCCS [Rochkind 1975] • RCS [Tichy 1982], • Newer Systems • Rational’s ClearCase(R) [Leblang 1994] • Adele Configuration Manager [Estublier and Casallas 1994]
Classical Tools • Integration of Parallel Changes • permanent versions • temporary versions • Semantic Conflicts • Logical Completeness
Conclusion • —There are multiple levels of parallel development. • —The activities within each of these levels cut across common files. • —Over the interval of a particular release (I6), the number of files changed by multiple MRs is 60% • —though we would expect the degree of awareness of the implications of these changes to be higher than those made within one day of each other • —There is a significant correlation between files with a high degree of parallel development and the number of defects