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Generalized Software Reliability Model (GSRM) Hironori Washizaki Waseda University National Institute of Informatics Twitter: @Hiro_Washi [email protected] http://www.washi.cs.waseda.ac.jp/ Kiyoshi Honda, Hironori Washizaki, YoshiakiFukazawa, “A Generalized Software Reliability Model Considering Uncertainty and Dynamics in Development,” PROFES 2013 NII Shonan Meeting, Oct 21, 2014
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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
COMPUTATIONAL INTELLIGENCE FOR SOFTWARE ENGINEERING
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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Page 1: Nii shonan-meeting-gsrm-20141021

Generalized Software Reliability Model

(GSRM)Hironori Washizaki

Waseda University

National Institute of InformaticsTwitter: @Hiro_Washi [email protected]

http://www.washi.cs.waseda.ac.jp/

Kiyoshi Honda, Hironori Washizaki, YoshiakiFukazawa, “A Generalized Software Reliability Model Considering Uncertainty and Dynamics in Development,” PROFES 2013

NII Shonan Meeting, Oct 21, 2014

Page 2: Nii shonan-meeting-gsrm-20141021

Motivation

• When can we release software?• How many efforts are necessary for further

testing?

2Time

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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

Page 4: Nii shonan-meeting-gsrm-20141021

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]4[Goel] A.L. Goel and K. Okumoto A non-homogeneous poisson process model for

software reliability and other performance measures, 1979

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#Defects

Actual

Predicted

Days

Case (Industry)

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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

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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.

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Dynamicity Uncertainty

A generalized software reliability model considering uncertainty and dynamics in development. PROFES ’13

Page 8: Nii shonan-meeting-gsrm-20141021

Uncertainty

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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.

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Dynamicity

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The number of developers is constant.

The number of developersper unit time changes at a certain time.

The number of developers per unit time increase near the end.

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Combination of Uncertainty and Dynamicity

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Similar to a logistic curve

Constant

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Prediction with Probability

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95% of defects are expected to be foundduring this term.

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Visualization integrated with Continuous Integration Tool

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Case (Industry)

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abyss_data-api abyss_data-api abyss_data-api

Module Current PredictedTotal

PredictedCurrent

PredictedEnd Day

XYZ 147 144 134 156

Almost all defects seem to be detected.Now more debugging rather than testing.

#Defects #Predicted Total DefectsPredication Error

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Case (OSS)

14Kiyoshi Honda, Hironori Washizaki, Yoshiaki Fukazawa, “Predicting the Release Time Based on a Generalized Software Reliability Model (GSRM),” COMPSAC’14

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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?