1. Keynote
Defect,
Defect, Defect
Sung Kim
The Hong Kong University of
Science and Technology

6. Program Analysis and Mining
(PAM) Group

7. Program Analysis and Mining
(PAM) Group

8. The First Bug
September 9, 1947

9. More Bugs

10. Finding Bugs
Verification
Testing
Prediction

11. Defect Prediction
42 24
14
Program Tool Future defects

12. Why Prediction?

13. Defect Prediction Model
D= 4.8 6+
0. 0 18L
F. Akiyama, “An Example of Software System Debugging,” Information Processing, vol. 71, 1971

14. Defect Prediction
Identifying New Metrics
Developing New Algorithms
Various Granularities

15. Defect Prediction
Identifying New Metrics
Developing New Algorithms
Various Granularities

16. Complex Files
a simple file
a complex file
Ostrand and Weyuker, Basili et al., TSE 1996, Ohlsson and Alberg, TSE 1996, Menzies et al., TSE 2007

17. Complex Files
a simple file
a complex file
Ostrand and Weyuker, Basili et al., TSE 1996, Ohlsson and Alberg, TSE 1996, Menzies et al., TSE 2007

18. Changes
Bell et al. PROMISE 2011, Moser et al., ICSE 2008, Nagappan et al., ICSE 2006, Hassan et al., ICSM 2005

19. Changes
Bell et al. PROMISE 2011, Moser et al., ICSE 2008, Nagappan et al., ICSE 2006, Hassan et al., ICSM 2005

20. View/Edit Patterns
Lee et al., FSE2011

21. Slide by Mik Kersten. “Mylyn – The task-focused interface” (December 2007, http://live.eclipse.org)

22. With Mylyn
Tasks are integrated
See only what you are working on
Slide by Mik Kersten. “Mylyn – The task-focused interface” (December 2007, http://live.eclipse.org)

23. * Eclipse plug-in storing and recovering task contexts

24. * Eclipse plug-in storing and recovering task contexts

25. <InteractionEvent … Kind=“ ” … StartDate=“ ” EndDate=“ ”
… StructureHandle=“ ” … Interest=“ ” … >
* Eclipse plug-in storing and recovering task contexts

26. Burst Edits/Views
Lee et al., FSE2011

27. Burst Edits/Views
Lee et al., FSE2011

28. Change Entropy
11
Low Entropy High Entropy
3 3 3 3 3
1 1 1 1
F1
F1 F2
F2 F3
F3 F4
F4 F5
F5 F6
F1 F7
F2 F8
F3 F9
F4 F10
F5
The number of changes in a period (e.g., a week) per file
Hassan, “Predicting Faults Using the Complexity of Code Changes,” ICSE 2009

29. Change Entropy
11
Low Entropy High Entropy
3 3 3 3 3
1 1 1 1
F1
F1 F2
F2 F3
F3 F4
F4 F5
F5 F6
F1 F7
F2 F8
F3 F9
F4 F10
F5
The number of changes in a period (e.g., a week) per file
Hassan, “Predicting Faults Using the Complexity of Code Changes,” ICSE 2009

30. Previous Fixes
Hassan et al., ICSM 2005, Kim et al., ICSE 2007

31. Previous Fixes
Hassan et al., ICSM 2005, Kim et al., ICSE 2007

32. Previous Fixes
Hassan et al., ICSM 2005, Kim et al., ICSE 2007

33. Network
Zimmermann and Nagappan, “Predicting Defects using Network Analysis on Dependency Graphs,”ICSE 2008

34. Network
Zimmermann and Nagappan, “Predicting Defects using Network Analysis on Dependency Graphs,”ICSE 2008

35. More Metrics
Complexity (Size)
CK
McCabe
OO
Process metrics
Halstead
Developer Count metrics
Change metrics
Entropy of changes (Change Complexity)
Churn (source code metrics)
# of changes to the file
Previous defects
Network measures
Calling structure attributes
Entropy (source code metrics)
0 5 10 15 20 25
# of publications (last 7 years)

36. Defect Prediction
Identifying New Metrics
Developing New Algorithms
Various Granularities

37. Classification
training instances complexity metrics
(metrics+ labels)
historical metrics
...
?
new instance
Prediction
Learner (classification)

38. Regression
training instances complexity metrics
(metrics+ values)
historical metrics
...
?
new instance
Prediction
Learner (values)

39. Active Learning
Anomaly Detection
System 1
Refinement
Sorted
Engine
Bug Reports 2 5
<<Refinement Loop>>
First Few Bug User
Reports 3 Feedback
4
Figure 4. Active Refinement Process
characteristics in a clone group. Then, the set ofet al., PROMISE 2012
Lo et al., “Active Refinement of Clone Anomaly Reports,” ICSE 2012, Lu anomalies or

40. Bug Cache
c h 10% files
e t most bug-prone
- f
re ad
s
is
p
on Lo
m
t
en
em
ac
pl
Nearby: co changes
re
all files
Kim et al., “Predicting Faults from Cached History,” ICSE 2007

41. Algorithms
Classification 21
Algorithms
Regression 18
Both 4
Etc. 4
0 5 10 15 20 25
# of publications (recent 7 years)
31

42. Defect Prediction
Identifying New Metrics
Developing New Algorithms
Various Granularities

43. Module/Binary/Package
Level

44. Module/Binary/Package
Level

45. File Level

46. File Level

47. Method Level
void foo () {
...
}
Hata et al.,“Bug Prediction Based on Fine-Grained Module Histories,” ICSE 2012

48. Method Level
void foo () {
...
}
Hata et al.,“Bug Prediction Based on Fine-Grained Module Histories,” ICSE 2012

49. Change Level
Development history of a file
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
... ... ... ...
Did I just
introduce
a bug?
Kim et al., "Classifying Software Changes: Clean or Buggy?" TSE 2009

50. Change Level
Development history of a file
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
... ... ... ...
Did I just
introduce
a bug?
Kim et al., "Classifying Software Changes: Clean or Buggy?" TSE 2009

51. More Granularities
Project/Release/SubSystem 3
Component/Module 8
Package 3
File 19
Class 8
Function/Method 2
Change/Hunk level 1
0 5 10 15 20
# of publications (recent 7 years)

52. Defect Prediction Summary
Identifying New Metrics
Developing New Algorithms
Various Granularities

53. Performance 11
Apache ArgoUML Eclipse Embedded Healthcare Microsoft Mozilla
System system
system
Hall et al., "A Systematic Review of Fault Prediction Performance in Software Engineering," TSE 2011 (Figure 2)

54. Performance
13 13
Class File Module Binary/plug-in
*For example plug-ins, binaries
*For example plug-ins, binaries
Figure 6. The granularity of the results
The granularity of the results
Hall et al., "A Systematic Review of Fault Prediction Performance in Software Engineering," TSE 2011 (Figure 6)

55. Performance
13 13
Class File Module Binary/plug-in
*For example plug-ins, binaries
*For example plug-ins, binaries
Figure 6. The granularity of the results
The granularity of the results
Hall et al., "A Systematic Review of Fault Prediction Performance in Software Engineering," TSE 2011 (Figure 6)

56. Defect prediction
totally works!

57. Defect prediction
totally works!

58. Done? Why are not using?

59. Detailed To Fix List
VS Buggy Modules

60. Detailed To Fix List
VS Buggy Modules

61. This is what developers want!

62. Defect Prediction 2.0
Finer Granularity
Noise Handling
New Customers

63. Defect Prediction 2.0
Finer Granularity
Noise Handling
New Customers

64. FindBugs
http://findbugs.sourceforge.net/

65. Performance of Bug Detection Tools
Tools' priority 1
FindBugs
Warnings
jLint
PMD
0 5 10 15 20
Precision (%)
Kim and Ernst, “Which Warnings Should I Fix First?” FSE 2007

66. RQ1: How Many False Negatives
! Defects missed, partially, or fully captured
! Warnings from a tool should also correctly explain in
detail why a flagged line may be faulty
! How many one-line defects are captured and explained
reasonably well (so called, “strictly captured”)?
Very high miss rates!
21
Thung et al., “To What Extent Could We Detect Field Defects?” ASE 2012

67. RQ1: How Many False Negatives
! Defects missed, partially, or fully captured
! Warnings from a tool should also correctly explain in
detail why a flagged line may be faulty
! How many one-line defects are captured and explained
reasonably well (so called, “strictly captured”)?
Very high miss rates!
21
Thung et al., “To What Extent Could We Detect Field Defects?” ASE 2012

68. Line Level Defect Prediction

69. Line Level Defect Prediction
We have seen this
bug in revision 100

70. Bug Fix Memories
Bug fix changes in
revision 1 .. n-1
……
Extract patterns in bug fix Memory
change history
Kim et al., “"Memories of bug fixes",” FSE 2006

71. Bug Fix Memories
Bug fix changes in
revision 1 .. n-1 Code to examine
……
Search for patterns
in Memory
Extract patterns in bug fix Memory
change history
Kim et al., “"Memories of bug fixes",” FSE 2006

72. Fix Wizard
public void setColspan(int colspan) throws WrongValueException{ public
if (colspan <= 0) throw new WrongValueException(...);
if ( colspan != colspan) { public
colspan = colspan; Objec
final Execution exec = Executions.getCurrent(); if (tar
MCla
if (exec != null && exec.isExplorer()) invalidate() ; Colle
smartUpdate(”colspan” Integer.toString( colspan));...
, MOp
class
public void setRowspan(int rowspan) throws WrongValueException{
if (rowspan <= 0) throw new WrongValueException(...);
if ( rowspan != rowspan) { public
rowspan = rowspan;
final Execution exec = Executions.getCurrent(); public
Objec
if (exec != null && exec.isExplorer()) invalidate(); if (tar
smartUpdate(”rowspan” Integer.toString( rowspan));...
, MCla
Colle
MAt
class
Figure 1: et al., “Recurring at v5088-v5089 in ZK
Nguyen Bug Fixes Bug Fixes in Object-Oriented Programs,” ICSE 2010

73. if (exec != null && exec.isExplorer()) invalidate();
smartUpdate(”rowspan” Integer.toString( rowspan));...
,
Fix Wizard in ZK
Figure 1: Bug Fixes at v5088-v5089
public void setColspan(int colspan) throws WrongValueException{
if (colspan <= 0) throw new WrongValueException(...);
Usage in method colspan) {
if ( colspan != colSpan Usage in method rowSpan
colspan = colspan;
IF IF IF IF
final Execution exec = Executions.getCurrent();
WrongValueException(exec
if .<init> != nullExecutions.getCurrent
&& exec.isExplorer()) invalidate() ;
WrongValueException .<init> Executions.getCurrent
smartUpdate(”colspan” Integer.toString( colspan));...
,
Execution.isExplorer Execution.isExplorer
IF
public void setRowspan(int rowspan) throws WrongValueException{ IF
if (rowspan <= 0) throw new WrongValueException(...);
if ( rowspan != rowspan) {
Auxheader.invalidate Auxheader.invalidate
rowspan = rowspan;
Usage in changed code
Auxheader.smartUpdate
final Execution exec = Executions.getCurrent(); Auxheader.smartUpdate
if (exec != null && exec.isExplorer()) invalidate();
smartUpdate(”rowspan” Integer.toString( rowspan));...
,
Figure 2: Graph-based Object Usages for Figure 1
Nguyen et al., Recurring Bug Fixes in Object-Oriented Programs,” ICSE 2010

74. Word Level Defect Prediction

75. Word Level Defect Prediction
Fix suggestion
...

76. Defect Prediction 2.0
Finer Granularity
Noise Handling
New Customers

77. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
commit
fixed bugs Bf
commit
commit
commit
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

78. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
commit
fixed bugs Bf
commit
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

79. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
commit
fixed bugs Bf
commit
linked fixed bugs Bfl
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

80. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
commit
fixed bugs Bf
commit
linked fixes Cfl linked fixed bugs Bfl
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

81. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
related,
commit
but not linked fixed bugs Bf
commit
linked fixes Cfl linked fixed bugs Bfl
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

82. Source Repository Bug Database
all commits C
commit all bugs B
commit commit
commit commit
bug fixes Cf related,
commit
but not linked fixed bugs Bf
commit
linked fixes Cfl linked fixed bugs Bfl
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

83. Source Repository Bug Database
all commits C
oise!
N all bugs B
commit
commit commit
commit commit
bug fixes Cf related,
commit
but not linked fixed bugs Bf
commit
linked fixes Cfl linked fixed bugs Bfl
commit
commit
linked via log messages
Bird et al., “Fair and Balanced? Bias in Bug-Fix Datasets,” FSE2009

84. How resistant a defect
prediction model is to noise?
1"
0.9"
0.8"
0.7"
Buggy%F'measure
SWT"
0.6"
0.5" Debug"
0.4" Columba"
0.3"
Eclipse"
0.2"
Scarab"
0.1"
0"
0" 0.1" 0.2" 0.3" 0.4" 0.5" 0.6"
(c)%Training%set%false%nega6ve%(FN)%&%false%posi6ve%(FP)%rate
Kim et al., “Dealing with Noise in Defect Prediction,” ICSE 2011

85. How resistant a defect
prediction model is to noise?
1"
0.9"
0.8"
0.7"
Buggy%F'measure
SWT"
0.6"
0.5" Debug"
0.4" Columba"
0.3"
Eclipse"
0.2"
Scarab"
0.1"
0"
0" 0.1" 0.2" 0.3" 0.4" 0.5" 0.6"
(c)%Training%set%false%nega6ve%(FN)%&%false%posi6ve%(FP)%rate
Kim et al., “Dealing with Noise in Defect Prediction,” ICSE 2011

86. How resistant a defect
prediction model is to noise?
1"
0.9"
0.8"
0.7"
Buggy%F'measure
SWT"
0.6"
0.5" Debug"
0.4" Columba"
0.3"
0.2"
0.1"
20% Eclipse"
Scarab"
0"
0" 0.1" 0.2" 0.3" 0.4" 0.5" 0.6"
(c)%Training%set%false%nega6ve%(FN)%&%false%posi6ve%(FP)%rate
Kim et al., “Dealing with Noise in Defect Prediction,” ICSE 2011

87. Closest List Noise
return Aj
Identification
F igure 9. The pseudo-code of the C LN I algorit
A
Kim et al., “Dealing with Noise in Defect Prediction,” ICSE 2011

88. Noise detection
performance
Precision Recall F-measure
Debug 0.681 0.871 0.764
SWT 0.624 0.830 0.712
(noise level =20%)
Kim et al., “Dealing with Noise in Defect Prediction,” ICSE 2011

89. Bug prediction using cleaned data
Noisey
100
75
SWT F-measure
50
25
0
0% 15% 30% 45%
Noise level

90. Bug prediction using cleaned data
Noisey Cleaned
100
75
SWT F-measure
50
25
0
0% 15% 30% 45%
Noise level

91. Bug prediction using cleaned data
Noisey Cleaned
100
75
SWT F-measure
50
25
76%
F-measure
with 45% noise
0
0% 15% 30% 45%
Noise level

92. ReLink
Source
code
repository Traditional
Unknown
heuristics
(link miner) links
Bug
database Recovering
links using
feature
Links
Features
Links
Combine
Links
Wu et al., “ReLink: Recovering Links between Bugs and Changes,” FSE 2011

93. ReLink
Source
code
repository Traditional
Unknown
heuristics
(link miner) links
Bug
database Recovering
links using
feature
Links
Features
Links
Combine
Links
Wu et al., “ReLink: Recovering Links between Bugs and Changes,” FSE 2011

94. ReLink Performance
ZXing
Projects
OpenIntents
Apache
0 20 40 60 80 100
F-measure
Traditional ReLink
Wu et al., “ReLink: Recovering Links between Bugs and Changes,” FSE 2011

95. Label Historical Changes
Change message:
“fix for bug 28434”
Rev 101 (with BUG) Rev 102 (no BUG)
... ...
... ...
... ...
fixed
... ...
Rev 1 Rev 100 Rev 101 Rev 102
... ... ... ...
...
...
…… ...
...
change ...
...
change ...
...
... ... ... ...
Development history of a file
Fischer et al, “Populating a Release History Database from Version Control and Bug Tracking Systems,” ICSM2003

96. Atomic Change
Change message:
“fix for bug 28434”
Rev 101 (with BUG) Rev 102 (no BUG)
... ...
setText(“t”) insertTab()
... ...
fixed
... ...
Fischer et al, “Populating a Release History Database from Version Control and Bug Tracking Systems,” ICSM2003

97. Composite Change
public TimeSeriesDataItem addOrUpdate(RegularTimePeriod period, double value)
hunk 1 677
678 }
return this.addOrUpdate(period, new Double(value));
}
return addOrUpdate(period, new Double(value)); this.
this.
public TimeSeries createCopy(RegularTimePeriod start, RegularTimePeriod end) this.
944 if (endIndex < 0) { if ((endIndex < 0) || (endIndex < startIndex)) {
hunk 2 945
946 }
emptyRange = true;
}
emptyRange = true; if (ti
|
ge
public boolean equals(Object object)
973 if (!ObjectUtilities.equal( if (!ObjectUtilities.equal(getDomainDescription(),
}
hunk 3 974
)){
getDomainDescription(), s.getDomainDescription() s.getDomainDescription())) {
975 return false; return false;
976 } }
pub
978 if (!ObjectUtilities.equal( if (!ObjectUtilities.equal(getRangeDescription(),
hunk 4 979
)){
getRangeDescription(), s.getRangeDescription() s.getRangeDescription())) {
}
980 return false; return false;
981 } }
JFree revision 1083
Figure 5. JFreeChart revision 1083.
Tao et al, “"How Do Software Engineers Understand Code Changes?” FSE 2012

98. Defect Prediction 2.0
Finer Granularity
Noise Handling
New Customers

99. Warning Developers
“Safe” Files
(Predicted as not buggy)
“Risky” Files
(Predicted as buggy)

100. Change Classification
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
Kim et al., "Classifying Software Changes: Clean or Buggy?" TSE 2009

101. Change Classification
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
“Safe” Files
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
“Risky” Files

102. Change Classification
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
“Safe” Files
Rev 1 Rev 2 Rev 3 Rev 4
... ... ... ...
... change ... change ... change ...
... ... ... ...
“Risky” Files

103. Defect prediction based
Change Classification
Debug UI
JDT
JEdit
Projects
PDE
POI
Team UI
0 0.20 0.40 0.60 0.80
F-measure
CC Cached CC

104. Warning Developers
“Safe” Location
(Predicted as not buggy)
“Risky” Location
(Predicted as buggy)

105. Test-case Selection

106. Test-case Selection
Executing
test cases

107. Test-case Selection
1.00
0.75
Baseline
APFD
0.50 History1
History2
0.25
0
R1.0 R1.1 R1.2 R1.3 R1.4 R1.5
Releases
Runeson and Ljung, “Improving Regression Testing Transparency and Efficiency with
History-Based Prioritization,” ICST 2011

108. Warning Prioritization

109. Warning Prioritization

110. Warning Prioritization
18"
16"
14"
12"
Precision)(%))
10"
8" History"
Tool"
6"
4"
2"
0"
0" 20" 40" 60" 80" 100"
Warning)Instances)by)Priority)
Kim and Ernst, “Which Warnings Should I Fix First?” FSE 2007

111. Other Topics
• Explanation
- Why it has been predicted as defect-prone?
• Cross-project prediction
• Cost effectiveness measures
• Active Learning/Refinement

112. Defect Prediction 2.0
New metrics
Algorithms
Coarse granularity 1.0

113. Defect Prediction 2.0
New metrics Finer granularity
Algorithms Noise Handling
Coarse granularity 1.0 New customers 2.0

114. Defect Prediction 2.0
New metrics Finer granularity
Algorithms Noise Handling
Corse granularity 1.0 New customers 2.0

115. 2013

116. MSR$2013:$Back$to$roots$
Tom$Zimmermann$ Alberto$Bacchelli$$
General'chair' Mining'Challenge'Chair'
Massimiliano$Di$Penta$and$Sung$Kim$
Program'co)chairs'

117. MSR$2013:$Back$to$roots$
Tom$Zimmermann$ Alberto$Bacchelli$$
General'chair' Mining'Challenge'Chair'
February
1 5
Massimiliano$Di$Penta$and$Sung$Kim$
Program'co)chairs'

118. Some slides/data are borrowed
with thanks from
• Tom Zimmermann, Chris Bird
• Andreas Zeller
• Ahmed Hassan
• David Lo
• Jaechang Nam,Yida Tao
• Tien Neguan
• Steve Counsell, David Bowes, Tracy Hall and David Gray
• Wen Zhang