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Nii shonan-meeting-gsrm-20141021


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“Predicting Release Time Based on Generalized Software Reliability Model”, by Hironori Washizaki
NII Shonan Meeting, Oct 21, 2014

Development environments have changed drastically, development periods are shorter than ever and the number of team members has increased. These changes have led to difficulties in controlling the development activities and predicting when the development will end. We propose a generalized software reliability model (GSRM) based on a stochastic process, and simulate developments that include uncertainties and dynamics. We also compare our simulation results to those of other software reliability models. Using the values of uncertainties and dynamics obtained from GSRM, we can evaluate the developments in a quantitative manner. Additionally, we use equations to define the uncertainty regarding the time required to complete a development, and predict whether or not a development will be completed on time.

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Nii shonan-meeting-gsrm-20141021

  1. 1. NII Shonan Meeting, Oct 21, 2014 Generalized Software Reliability Model (GSRM) Hironori Washizaki Waseda University National Institute of Informatics Twitter: @Hiro_Washi Kiyoshi Honda, Hironori Washizaki, YoshiakiFukazawa, “A Generalized Software Reliability Model Considering Uncertainty and Dynamics in Development,” PROFES 2013
  2. 2. Motivation • When can we release software? • How many efforts are necessary for further testing? 2 Time
  3. 3. Software Reliability Model (SRM) 3 Counting the defects a day or a week Approximate actual data to a curve and predict defects At this time, 95% of all defects will be found Prediction model
  4. 4. Types of SRM • Statistic analysis model – From actual data approximate to a curve. – Gompertz model – Logistic model • Stochastic process model – The detection of defects follows stochastic process – Non-homogeneous Poisson process(NHPP) model [Goel] [Goel] A.L. Goel and K. Okumoto A non-homogeneous poisson process model for 4 software reliability and other performance measures, 1979
  5. 5. 5 #Defects Actual Predicted Case (Industry) Days
  6. 6. Further Challenges in SRM • Uncertainty – Actual projects have many uncertain elements which cause defects. – E.g. changes of specifications • Dynamicity – Actual projects have some time dependency. – E.g. changes of developers 6
  7. 7. Idea: Generalized SRM • Conventional Logistic Model • Assumptions – Number of defects that can be found is variable depending on time. – Number of defects that can be found contains uncertainty, which can be simulated with Gaussian white noise. 7 Dynamicity Uncertainty A generalized software reliability model considering uncertainty and dynamics in development. PROFES ’13
  8. 8. Uncertainty 8 the uncertainty is greater at the start of the project than at the end. The uncertainty is constant at any given time. The uncertainty increases near the end.
  9. 9. Dynamicity 9 The number of developers is constant. The number of developers per unit time changes at a certain time. The number of developers per unit time increase near the end.
  10. 10. Combination of Uncertainty and Dynamicity 10 Similar to a logistic curve Constant
  11. 11. Prediction with Probability 11 95% of defects are expected to be found during this term.
  12. 12. 12 Visualization integrated with Continuous Integration Tool
  13. 13. Case (Industry) 13 #abyss_Defects data-api Predication abyss_data-api Error #Predicted abyss_data-Total api Defects Module Current Predicted Total Predicted Current Predicted End Day XYZ 147 144 134 156 Almost all defects seem to be detected. Now more debugging rather than testing.
  14. 14. Case (OSS) Kiyoshi Honda, Hironori Washizaki, Yoshiaki Fukazawa, “Predicting the Release Time 14 Based on a Generalized Software Reliability Model (GSRM),” COMPSAC’14
  15. 15. Open Research Questions • How to Predict Uncertainty and Dynamicity? • How to dynamically adapt prediction? • Can we integrate testing and debugging techniques with (G)SRM? • Any relations among Predicted Reliability and other measures such as Testing Coverage and Mutation Testing Scores?