Software developers, code ownership, anti-patterns

1. IMPACT OF CODE OWNERSHIP
ON ATIPATTERNS
Stéphane BUNOD
Engineering school student at Polytech’Montpellier
3 month internship
Supervisor : Foutse KHOMH

2. OUTLINE
 Context
 Goal
 Implementation
 Results
 Conclusion
 Personal experience

3. CONTEXT
 Foutse’s research interests
 Developping techniques and tools to assess the quality of systems
 Design patterns, design defects : their impact on the quality of systems and their
evolution in systems
 Foutse “Antipatterns are more fault prone” . 2012
 Christian Bird. Don’t Touch My Code! Examining the Effects of Ownership on
Software Quality. 2011

4. GOAL

5. IMPLEMENTATION – EXISTING WORK
 Previous work from Francis NAHM:
 List of AntiPatterns for each version of the Argouml project
(APs example : ComplexClass, LongMethod, LongParameterList)

6. IMPLEMENTATION – COLLECT
 Collect information about the Argouml project:
 SVN log

7. IMPLEMENTATION – WHAT IS INTERESTING IN « SVN LOG »

8. IMPLEMENTATION – KEEP INTERESTING INFORMATION
 Get the list of contributors
 Get the date of commits
 Get the files/classes that had been modified

9. IMPLEMENTATION – EVALUATE MAJOR CONTRIBUTOR RATE
Major contributor: A developer who has made changes to a component and whose
ownership is at or above X% is a major contributor to the component and a commit
from such a developer is a major contribution.
3rd quartile of all contributors statistics on each classes : 71%

10. IMPLEMENTATION – ADD INFORMATION OF MC ON EACH VERSION
 Know the kind of contributor for each version on each class.
 Add it beside the number of AntiPatterns on each version of each class.

11. IMPLEMENTATION – WHAT THE CSV LOOKS LIKE

12. IMPLEMENTATION – METHOD TO ESTIMATE THE EVOLUTION OF A CLASS
List of the occurrence of AntiPatterns for each class.
Example: [5, 3, 4, 4, 1, 2, 5]
[0]: A-A-A-A-A-S
[1]: D-D-A-A-D
[2]: S-A-A-D
[3]: A-A-D
[4]: D-D
[5]: D
A = 11 ; D = 8 ; S = 2
 A > D > S  This class is considered to have a global amelioration tendency

13. IMPLEMENTATION – DIFFERENT CATEGORIES OF LIST
 Classes with only Major Contributor (MC) on each version of the project.
 Classes without any MC.
 Classes with a MC, only on the first version.
 Classes with a developer who becomes MC after few versions without any.
 Classes where there is no longer MC after few versions with a MC.

14. RESULTS
Only MC
No MC
Only MC on
the 1st
version
Stable
58%
73,63%
74,40%
87,13%
79,18%
Amelioration
24%
11,55%
7,76%
1,98%
14,46%
Degradation
18%
14,82%
20,84%
10,89%
6,36%
Become MC
No longer MC

15. CONCLUSION
Linus Law. “Given a large enough developers, almost every problem will be
characterized quickly and the fix will be obvious to someone“
 AntiPatterns have the same characteristics of Bugs correlate with
ownership.
 Of course, this work should be reproduced on other projects.

16. PERSONAL EXPERIENCE
 Lab experience
 Met new people
 Learnt Python language (enjoyed coding for once)
 Not sure I would be a good researcher ^^