Windows: 2 years ( traditional ) Debian: 1 year ( traditional ) Oracle: 1 year MySQL: 4 weeks Eclipse: 6 weeks Fedora: 3-6 months Shared dev : cvs Shared knowledge: know bugs/fixes are in cvs -> dig it to share -> knowledge bases.
Developers try/share new ideas, implementation, algorithms, new process Having a community is the motivation of developers. Feedback control system: a system is better if it has feedback. Multi level
Fast/effective defect-correction cycle: both quality and security. Users/testers find bugs -> developers fix. Findbugs: jlint: find bug prone code and bug itself.