Presented at SAM 2015 (2nd International Workshop on Software Architecture and Metrics): http://www.sei.cmu.edu/community/sam2015/speakers/ Nowadays we have tools that compute a myriad of metrics and throw at us thousands of warnings. Managers are gazing ecstatically at complex dashboards full of complex and vividly colored charts and trend lines. Sophisticated "technical debt calculators" are converting, with great boldness, internal quality issues to scary financial figures. With such an impressive arsenal of methodologies, techniques, and tools, software projects should be under full control. Except they are not! Often, metrics leave us clueless on how to improve the quality of our software; even worse, following blindly the goal of fixing some metric values usually leads to a degradation of a system's quality. In this talk, I will share some of the practical lessons learned on how to use software metrics to actually improve a system's design. I will also discuss the need to find new ways of correlating the various sources of information about a project, in order to move from raw data to insightful knowledge that can lead to real improvement actions.

1. Measuring Software:
From Data to Actionable Knowledge
16 May 2015
International Workshop on Software Architecture and Metrics
Radu Marinescu
radumarinescu@me.com
@radu_marinescu

3. ogo
lori
Culoare pentru o institu]ie unic - clar, curat, u[or de recunoscut - culoarea
este elementul cel mai u[or de recunoscut, albastru indigo reflect personalitatea
institu]ieide<nv]m>ntsuperiortehnic-ferm,puternic,darintrospectiv,valorizator.
Este o combina]ie de albastru [i ro[u, <n care dominant este albastrul cu atributele
sale introspective. Griul neutru pune <n valoare albastrul, accentu>nd valorile sale.

4. ogo
ulori
Culoare pentru o institu]ie unic - clar, curat, u[or de recunoscut - culoarea
este elementul cel mai u[or de recunoscut, albastru indigo reflect personalitatea
institu]ieide<nv]m>ntsuperiortehnic-ferm,puternic,darintrospectiv,valorizator.
Este o combina]ie de albastru [i ro[u, <n care dominant este albastrul cu atributele
sale introspective. Griul neutru pune <n valoare albastrul, accentu>nd valorile sale.

5. Logo
culori
Culoare pentru o institu]ie unic - clar, curat, u[or de recunoscut - culoarea
este elementul cel mai u[or de recunoscut, albastru indigo reflect personalitatea
institu]ieide<nv]m>ntsuperiortehnic-ferm,puternic,darintrospectiv,valorizator.
Este o combina]ie de albastru [i ro[u, <n care dominant este albastrul cu atributele
sale introspective. Griul neutru pune <n valoare albastrul, accentu>nd valorile sale.

6. Logo
culori
Culoare pentru o institu]ie unic - clar, curat, u[or de recunoscut - culoarea
este elementul cel mai u[or de recunoscut, albastru indigo reflect personalitatea
institu]ieide<nv]m>ntsuperiortehnic-ferm,puternic,darintrospectiv,valorizator.
Este o combina]ie de albastru [i ro[u, <n care dominant este albastrul cu atributele
sale introspective. Griul neutru pune <n valoare albastrul, accentu>nd valorile sale.

7. Michele Lanza
Radu Marinescu
Object-Oriented
Metrics
in Practice
Using Software Metrics to
Characterize, Evaluate, and Improve
the Design of Object-Oriented Systems
Foreword by Stéphane Ducasse
1 3
1000+reprinted2010/2015
MIPICSME’14

8. inFusion

9. inFusion

10. inFusion

11. inFusion

12. seentoo much…
I have

13. time & money
wasted on…

14. “hide & seek”
bug chasing

15. playing futile
numbers games

16. code being
thrown away

17. but also…

18. myriads of
useless papers

19. tens of
“mayfly”
prototypes

20. a true story…

22. 180.9
(12 subsystems)
(17 methods)
(3 subsystems)
NOW6 months ago
(1 class)
(22
(10 methods)
(32 classes)
(16 classes)
(28 classes)
(120 methods)

24. 180.9
(12 subsystems)
(17 methods)
(3 subsystems)
NOW6 months ago
(1 class)
(22
(10 methods)
(32 classes)
(16 classes)
(28 classes)
(120 methods)

25. 180.9
(12 subsystems)
(17 methods)
(3 subsystems)
NOW6 months ago
(1 class)
(22
(10 methods)
(32 classes)
(16 classes)
(28 classes)
(120 methods)

26. 180.9
(12 subsystems)
(17 methods)
(3 subsystems)
NOW6 months ago
(1 class)
(22
(10 methods)
(32 classes)
(16 classes)
(28 classes)
(120 methods)

27. CYCLOMATIC
COMPLEXITY

28. !This is not an
isolated story

30. use of metrics
(and other code analyses) in

31. use of metrics
(and other code analyses) in
misuse

32. http://nemo.sonarqube.org/

33. 12 Person-Years
http://nemo.sonarqube.org/

34. 12 Person-Years
1 issues / 8 LOC
http://nemo.sonarqube.org/

35. 12 Person-Years
1 issues / 8 LOC1 “key” issue / 140 LOC
http://nemo.sonarqube.org/

36. 12 Person-Years
1 issues / 8 LOC1 “key” issue / 140 LOC
OMG! How is an “E”?!
http://nemo.sonarqube.org/

37. Picture from http://www.savvykidsofarkansas.com/event/the-boy-who-cried-wolf/

38. http://nemo.sonarqube.org/

39. The most efficient 7 weeks in the
history of software development…
http://nemo.sonarqube.org/

40. The most efficient 7 weeks in the
history of software development…
http://nemo.sonarqube.org/

41. The most efficient 7 weeks in the
history of software development…
16.5 Person-Years of Technical Debt vanished!
http://nemo.sonarqube.org/

42. The most efficient 7 weeks in the
history of software development…
16.5 Person-Years of Technical Debt vanished!
http://nemo.sonarqube.org/

44. Let’s zoom-in…

45. http://nemo.sonarqube.org/

46. http://nemo.sonarqube.org/

47. http://nemo.sonarqube.org/

48. http://nemo.sonarqube.org/

49. http://nemo.sonarqube.org/
are these separate problems?

50. http://nemo.sonarqube.org/

51. http://nemo.sonarqube.org/

52. who “authorized”
these thresholds?
http://nemo.sonarqube.org/

53. http://nemo.sonarqube.org/

54. http://nemo.sonarqube.org/

55. reducing CYCLO takes
only 1 min / branch ?
http://nemo.sonarqube.org/

56. reducing CYCLO takes
only 1 min / branch ?
reducing CYCLO for class
is easier (137’) than for
methods (285’)
http://nemo.sonarqube.org/

57. http://nemo.sonarqube.org/

58. http://nemo.sonarqube.org/

59. http://nemo.sonarqube.org/

60. never knew it’s so easy
to change a signature!
http://nemo.sonarqube.org/

61. but what if…

62. but what if…

63. http://nemo.sonarqube.org/

64. solving duplication
does only depend on
the number of blocks?
http://nemo.sonarqube.org/

65. …are these 2 cases equally easy?

66. …

67. Image from http://imgur.com/gallery/iWKad22

68. Let’s summarize…

70. 1 Irrelevant Warnings

71. 1 Irrelevant Warnings
2 Misleading Debt Quantification

72. 1 Irrelevant Warnings
2 Misleading Debt Quantification
3 Toxic/Stupid Refactoring Advices

73. 1 Irrelevant Warnings
2 Misleading Debt Quantification
3 Toxic/Stupid Refactoring Advices
4 Phony Thresholds

74. Why
?

75. Technical Debt

76. The first scary things was bugs

77. http://www.google.com/imgres?imgurl=http://micheltriana.com/
wp-content/uploads/2010/12/
resharper-8x6.png&imgrefurl=http://micheltriana.com/
2010/12/01/configuring-resharper-code-analysis/
&h=459&w=640&tbnid=MFJydOmaXXj3xM:&zoom=1&docid=e0
dqbvDRdbGVSM&ei=xOEcVaXfOsiWaoa6gJAI&tbm=isch&client
=safari&ved=0CBwQMygAMAA

78. http://www.google.com/imgres?imgurl=http://micheltriana.com/
wp-content/uploads/2010/12/
resharper-8x6.png&imgrefurl=http://micheltriana.com/
2010/12/01/configuring-resharper-code-analysis/
&h=459&w=640&tbnid=MFJydOmaXXj3xM:&zoom=1&docid=e0
dqbvDRdbGVSM&ei=xOEcVaXfOsiWaoa6gJAI&tbm=isch&client
=safari&ved=0CBwQMygAMAA

83. but then we realised…

84. Most maintenance effort goes into
understanding
messy code
47%
19%
6%
28%
Testing Documenting
Coding Understanding
M. Ben-Menachem and G. S. Marliss. Software quality: Producing practical, consistent software. International Thomson Computer Press, 1997

85. Bugs
error-prone

86. Bugs
Time
hard to maintain
error-prone

87. … and bugs also usually hide in
messy code

88. Checkstyle

89. !We missed
an essential distinction

90. =

91. Strategic Flaws
Tactical Flaws
Execution Flaws
…system
…statements
…classes
and functions
How do I
design the…

92. Execution flaws Tactical flaws

93. Execution flaws Tactical flaws

94. Execution flaws Tactical flaws

95. Execution flaws Tactical flaws

96. Execution flaws Tactical flaws

99. PSA

100. PSA Gleason

101. PSA Gleason

102. PSA Gleason

103. ?what about tactical problems

104. public class TarHeader{
/**
* The entry's name.
*/
public StringBuffer name;
/**
* The entry's permission mode.
*/
public int mode;
/**
* The entry's user id.
*/
public int userId;
/**
* The entry's group id.
*/
public int groupId;
}

105. public
/**
* The entry's name.
*/
/**
* The entry's permission mode.
*/
int
/**
* The entry's user id.
*/
/**
* The entry's group id.
*/
int
}
public
public
public
public

106. public
/**
* The entry's name.
*/
/**
* The entry's permission mode.
*/
int
/**
* The entry's user id.
*/
/**
* The entry's group id.
*/
int
}
public
public
public
public
Data
Class

107. public
/**
* The entry's name.
*/
/**
* The entry's permission mode.
*/
/**
* The entry's user id.
*/
/**
* The entry's group id.
*/
int
}

108. public
/**
* The entry's name.
*/
/**
* The entry's permission mode.
*/
/**
* The entry's user id.
*/
/**
* The entry's group id.
*/
int
}
private
private
private
private

109. public
/**
* The entry's name.
*/
/**
* The entry's permission mode.
*/
/**
* The entry's user id.
*/
/**
* The entry's group id.
*/
int
}
private
private
private
private
Encapsulate public data
(in TarHeader)1

110. compile errors!

111. public class {
public void parseTarHeader( TarHeader hdr, byte[] header ){
int offset = 0;
hdr.name = TarHeader.parseName( header, offset,
TarHeader.NAMELEN );
offset += TarHeader.NAMELEN;
hdr.mode = (int)TarHeader.parseOctal( header, offset,
TarHeader.MODELEN );
offset += TarHeader.MODELEN;
hdr.userId = (int)TarHeader.parseOctal( header, offset,
TarHeader.UIDLEN );
offset += TarHeader.UIDLEN;
hdr.groupId = (int)TarHeader.parseOctal( header, offset,
TarHeader.GIDLEN );
}
TarEntry

112. public
public
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader
}
TarEntry
TarHeader hdr
hdr.name
hdr.mode
hdr.userId
hdr.groupId
parseTarHeader

113. public
public
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader
}
TarEntry
TarHeader hdr
hdr.name
hdr.mode
hdr.userId
hdr.groupId
parseTarHeader
Move the method
(TarEntry > TarHeader)1

114. public
public
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader.
offset += TarHeader.
hdr.
TarHeader
}
TarEntry
TarHeader hdr
hdr.name
hdr.mode
hdr.userId
hdr.groupId
parseTarHeader
Encapsulate public data
(in TarHeader)2
Move the method
(TarEntry > TarHeader)1

115. however …

116. public
public
int
hdr.
header, offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader
}
public
int
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
long
offset = TarHeader.getLongOctalBytes
( size, outbuf, offset, TarHeader.
}
hdr.mode = (int)TarHeader.parseOctal( header,
hdr.mode = (int)TarHeader.parseOctal( header,
offset, TarHeader.MODELEN );
offset, TarHeader.MODELEN );
offset += TarHeader.MODELEN;
offset += TarHeader.MODELEN;
hdr.userId = (int)TarHeader.parseOctal( header,
hdr.userId = (int)TarHeader.parseOctal( header,
offset, TarHeader.UIDLEN );
offset, TarHeader.UIDLEN );
parseTarHeader
writeEntryHeader

117. public
public
int
hdr.
header, offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader
}
public
int
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
long
offset = TarHeader.getLongOctalBytes
( size, outbuf, offset, TarHeader.
}
hdr.mode = (int)TarHeader.parseOctal( header,
hdr.mode = (int)TarHeader.parseOctal( header,
offset, TarHeader.MODELEN );
offset, TarHeader.MODELEN );
offset += TarHeader.MODELEN;
offset += TarHeader.MODELEN;
hdr.userId = (int)TarHeader.parseOctal( header,
hdr.userId = (int)TarHeader.parseOctal( header,
offset, TarHeader.UIDLEN );
offset, TarHeader.UIDLEN );
parseTarHeader
writeEntryHeader
Duplicated
Code

118. public
public
int
hdr.
header, offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader
}
public
int
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
long
offset = TarHeader.getLongOctalBytes
( size, outbuf, offset, TarHeader.
}
hdr.mode
hdr.mode
offset, TarHeader.
offset, TarHeader.
offset += TarHeader.
offset += TarHeader.
hdr.userId
hdr.userId
offset, TarHeader.
offset, TarHeader.
parseTarHeader
writeEntryHeader
Extract method
(by factoring out the duplicated code)1

119. public
public
int
hdr.
header, offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader
}
public
int
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
long
offset = TarHeader.getLongOctalBytes
( size, outbuf, offset, TarHeader.
}
hdr.mode
hdr.mode
offset, TarHeader.
offset, TarHeader.
offset += TarHeader.
offset += TarHeader.
hdr.userId
hdr.userId
offset, TarHeader.
offset, TarHeader.
parseTarHeader
writeEntryHeader
Extract method
(by factoring out the duplicated code)1
Move the newly created method
(in TarHeader)2

120. public
public
int
hdr.
header, offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader
}
public
int
hdr.
offset, TarHeader.
offset += TarHeader.
hdr.
offset, TarHeader.
long
offset = TarHeader.getLongOctalBytes
( size, outbuf, offset, TarHeader.
}
hdr.mode
hdr.mode
offset, TarHeader.
offset, TarHeader.
offset += TarHeader.
offset += TarHeader.
hdr.userId
hdr.userId
offset, TarHeader.
offset, TarHeader.
parseTarHeader
writeEntryHeader
Extract method
(by factoring out the duplicated code)1
Move the newly created method
(in TarHeader)2
Encapsulate public data
(in TarHeader)3

121. yet, there is an alternative solution…

123. Move data
(TarHeader > TarEntry)1

124. Move data
(TarHeader > TarEntry)1
Encapsulate public data
(in TarEntry)2

125. vs.
Extract method
(out of the duplicated code)1
Move the newly created method
(in TarHeader)2
Encapsulate public data
(in TarHeader)3
Move data
(TarHeader > TarEntry)1
Encapsulate public data
(in TarEntry)2

126. vs.
Which solution is best?
Extract method
(out of the duplicated code)1
Move the newly created method
(in TarHeader)2
Encapsulate public data
(in TarHeader)3
Move data
(TarHeader > TarEntry)1
Encapsulate public data
(in TarEntry)2

127. Only the developer
who knows the context
can decide!

128. ?How to dealwith
tactical flaws

129. start with
symptom indicators
Checkstyle

130. Lorenz, Kidd, 1994
Chidamber, Kemerer, 1994
LOC - number of lines of code
CYCLO - cyclomatic complexity of a function
NOF - number of functions
FANOUT - outgoing coupling
NOA - number of attributes
DIT - depth of inheritance tree
TCC - tight class cohesion
…

131. The problem is…

132. Image from pickywallpapers.com

134. !Tactical flaws must be treated as
first-class entities

135. !…and symptoms must be
aggregated

136. for example…

137. from S.Demeyer, S.Ducasse, O.Nierstrasz - Object-Oriented Reengineering Patterns, 2003

138. from S.Demeyer, S.Ducasse, O.Nierstrasz - Object-Oriented Reengineering Patterns, 2003

139. from S.Demeyer, S.Ducasse, O.Nierstrasz - Object-Oriented Reengineering Patterns, 2003

140. or another example…

141. God Classes
use data from small data-classes,
centralize the intelligence of the system,
and do everything.
A.Riel, 1996

142. God Classes
break encapsulation, and
are complex, and
are not cohesive.
A.Riel, 1996

143. ATFD > FEW
Class uses directly more than a
few attributes of other classes
WMC ≥ VERY HIGH
Functional complexity of the
class is very high
TCC < ONE THIRD
Class cohesion is low
AND GodClass
from M.Lanza, R.Marinescu - Object-Oriented Metrics in Prac

144. but there is
one more problem
when dealing with metrics…

145. Thresholds

146. who “authorized”
these thresholds?

147. Experts, right?
Image from http://www.dilbert.com

149. 5 projects?!?!
< 100 classes?!?!

150. Michele Lanza
Radu Marinescu
Object-Oriented
Metrics
in Practice
Using Software Metrics to
Characterize, Evaluate, and Improve
the Design of Object-Oriented Systems
Foreword by Stéphane Ducasse
1 3

151. Michele Lanza
Radu Marinescu
Object-Oriented
Metrics
in Practice
Using Software Metrics to
Characterize, Evaluate, and Improve
the Design of Object-Oriented Systems
Foreword by Stéphane Ducasse
1 3
37/45 projects…

153. 4800 projects(SourceForge)
300.000.000 lines of code

154. 4800 projects(SourceForge)
300.000.000 lines of code inFusion

155. 4800 projects(SourceForge)
300.000.000 lines of code inFusion

156. Wrapping it up…

157. #1
Distinguish tactical flaws
from execution flaws

158. #2
Don’t correct tactical flaws
by fixing isolated symptoms

159. #3
Correcting tactical flaws
requires exploration tools

160. #3
Correcting tactical flaws
requires exploration tools
powerful

161. Flaw Summary

162. Flaw Summary
Visualization
Metrics
Related flaws
Source Highlighter
Dependency Breakout

163. #4
Improve
technical debt calculators

164. #5
Build massive collection of
curated measurement data

165. “ ”
A single arrow is easily broken, but not ten in a bundle.
Japanese proverb

166. Measuring Software:
From Data to Actionable Knowledge
16 May 2015
International Workshop on Software Architecture and Metrics
Radu Marinescu
radumarinescu@me.com
@radu_marinescu