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Global Software Development in Global Software Development in - - PowerPoint PPT Presentation
Global Software Development in Global Software Development in - - PowerPoint PPT Presentation
Global Software Development in Global Software Development in Global Software Development in the FreeBSD Project the FreeBSD Project the FreeBSD Project Diomidis Spinellis Diomidis Spinellis Athens University of Economics and Business
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FreeBSD
Complete operating system Derived from BSD Unix Focus on stability and reliability
– Yahoo’s s servers – Part of Apple’s Max OS X
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Development
~350 developers
– Documentation
Third party application ports ~12000 Operating system utilities ~9.8MLoC Kernel ~2.8MLoC
Documentation
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Development Facilities
CVS (10 years of historical data; >938k) Problem reports (>95k) Mailing lists (>100) Tinderbox Web site
– Developer’s handbook – Release engineering – Browsable CVS – Mailing lists – PRs
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Development Process
Unpaid volunteers Teams
– Core – Release engineering – Security – Ports – Donations
Committer etiquette Mentoring
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Global Development
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Around the Globe
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Division of Work
500 1000 1500 2000 2500 3000 Africa Asia Australia Europe North America South America KLoC
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Hold and Advance
Work type per area
0% 20% 40% 60% 80% 100% Africa Asia Australia Europe North America South America KLoC Main Branch
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… and Fix
Africa 1% Asia 13% Europe 41% South America 2% North America 36% Australia 7%
Closed GNATS entries per area
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Roads and Buildings
Work type per area
0% 20% 40% 60% 80% 100% Africa Asia Europe South America North America Australia ports doc www src
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Round the Clock
50 100 150 200 250 300 4 8 12 16 20 Average LOC per day Time (UTC)
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Passing Work Around
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Files Modules All Granule Days >8h by different committers >8h by the same committer Next day commits
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Productivity and Quality
+Round the clock development +Software and hardware diversity
- Lack of face-to-face communication
- Asynchronous communication
?A more rigorous process is required ?Cultural diversity
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Productivity
More developers produce more software (base case)
200 400 600 800 1000 10 20 30 40 50 KLoC Number of developers
r=0.67 (95% CI)
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Productivity
… but developer distance doesn’t affect productivity.
r=-0.14 (95% CI)
200 400 600 800 1000 2000 4000 6000 8000 10000 12000 14000 16000 18000 KLoC Developer distance
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Code Style
20 40 60 80 100 10 20 30 40 50 60 70 80 90 % of non-adhering lines Number of developers in the annotated file
r=0.05 (95% CI)
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Defect Density
0.2 0.4 0.6 0.8 1 20 40 60 80 100 120 140 160 180 200 PRs per commit Number of developers
r=0.07 (95% CI)
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Human Interactions
Look for neighbors
– Cooperating developers – Mentors and mentees
Jan Van Haasteren: Neighbours
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Cooperating developers
Mean distance between
– any two FreeBSD developers: 6,701km
4010 instances of commits
– Same file – Same day – Different developers – Mean distance: 6,489km
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Mentors and mentees
18 8.8 5.0 3.8 0.7 M/M 19 9.3 6.7 7.8 2.2 Any Max ¾ Mean Media ¼ Min
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