Presented at ICSME 2019 https://doi.org/10.1109/ICSME.2019.00088

1. CanAutomatedImpactAnalysis
TechniqueHelpPredicting
DecayingModules?
Tokyo Institute of
Technology
Natthawute
Sae-Lim
Shinpei
Hayashi
Motoshi
Saeki
[ Smelling things by Tjarko Busink: https://www.flickr.com/photos/sjekkiebunzing/13009723845/ ]

2. [ Smelling things by Tjarko Busink: https://www.flickr.com/photos/sjekkiebunzing/13009723845/ ]
Bad Smell

3. Code Smell
3
An indicator of a design flaw/problem
in the source code
One of the factors that cause technical debt
Increases code component’s fault-proneness
Detector
Code smells
Refactoring
Class A
{
__________
__________
__________
__________
}
Source code How to
prevent?

4. Non
Smell
Decaying Modules:
Modules going to be smelly
4
Smell
Module
Decaying
Index
0
1
Smell
Severity
Decaying modules ⇒ whose smell degree
has increased from the previous release
Time

5. 5
approx. 19% of modules
were decaying modules
in each release
’’
Sae-Lim et al.,“Toward Proactive Refactoring:An Exploratory Study on Decaying Modules”, Proc. IWoR 2019.
[ 3/4" 285HV Grid 1749 by Peter Kemmer: https://www.flickr.com/photos/pkmousie/2225340795/ ]
decaying modules are
more likely to get decayed
in later releases
’’

6. Decaying Module Prediction
l Existing approach: code quality metric-based
l Use of task context
– Using IR-based impact analysis (IA) to connect
change descriptions to modules may contribute to
improving the prediction performance
6
Source code Source code
Bug 123
When
click…
Changes
Bug 123
When
click…
Bug 123
When
click…
Ver 1.0 Ver 2.0
Implementation

7. Research Questions
RQ1:
Can IR-based impact analysis
improve prediction performance?
7[ protractors by Dean Hochman: https://www.flickr.com/photos/deanhochman/14481958642/ ]
RQ2:
How can we further improve
prediction performance?

8. Baseline
8
All data
Training
data
Static
Analyzer
Detector
Model
Construction
1._______
2._______
3._______
4._______
Current RecentHistorical
Code quality
Decaying
modules
1…
2…
3…
Predicted results
Test data
Static
Analyzer
Trained model
Vn
Vn+1
1._______
2._______
3._______
4._______
Current RecentHistorical
Code quality
Pantiuchina, et al.:“Towards just-in-time refactoring recommenders”, Proc. ICPC 2018.

9. Baseline + Impact Analysis
10
Bug 123
When
click…
Bug 123
When
click…
Bug 123
When
click…
Change
descriptions
Impact
Analysis
Main()
xxx;;
Source code
Estimated
module list
Bug 123
When
click…
Bug 123
When
click…
Bug 123
When
click…
Change
descriptions
Impact
Analysis
Main()
xxx;;
Source code
Estimated
module list
Model
Construction
1._______
2._______
3._______
4._______
Current RecentHistorical
Code quality
Decaying
modules
1…
2…
3…
Predicted results
Trained model
1._______
2._______
3._______
4._______
Current RecentHistorical
Code quality

10. Dataset
Target smell: God Class
11
Project Period (years) # Releases
Accumulo 6 30
Ambari 6 33
Hive 13 28
Derby 7 33

11. Can IR-based IA improve
prediction performance?
12
RQ
1

12. Can IR-based IA improve
prediction performance?
13
RQ
1
If IA is perfect, accuracy becomes very high.
Future direction: Improving IA

13. Delete false positives (FPs)
Insert true positives (TPs)
How can we further
improve the performance?
14
RQ
2
Change
description
Bug 123
When
click… 1Oracle: 2 3 4 5
IA 1 2
1 2
1 2 3
Result:
Simulating IA results of different accuracy:

14. How can we further
improve the performance?
15
RQ
2
FP
Dec. Ratio
TP
Inc. Ratio
0
1
1
0
Accumulo

15. How can we further
improve the performance?
16
RQ
2
HiveDerby
Adding TPs (recall!) should be done first
AccumuloAmbari
Precision
Recall
IA accuracy↑ leads to Performance↑

16. CanAutomated
ImpactAnalysis
TechniqueHelp
Predicting
DecayingModules?
[ Smelling things by Tjarko Busink: https://www.flickr.com/photos/sjekkiebunzing/13009723845/ ]
Can IR-Based IA improve
prediction performance?
11
RQ
1
If IA is perfect, accuracy becomes very high
Future direction: Improving IA
Non
Smell
Decaying Modules:
Modules going to be smelly
3
Smell
Module
Decaying
Index
0
1
Smell
Severity
Decaying modules ⇒ whose smell degree
has increased from the previous release
Time
How can we further
improve the performance?
16
RQ
2
HiveDerby
Adding TPs (recall!) should be done first
AccumuloAmbari
Precision
Recall
IA accuracy↑ leads to Performance↑