Global Software Development in the FreeBSD ProjectDiomidis SpinellisAthens University of Economics and Businessand FreeBSD

OutlineFreeBSDMethodologyFindingsGlobal developmentProductivity and qualityHuman interactions

RationaleRough side of global software developmentSetting benchmarks in global outsourcingIf it works there, it works everywherePractices that workRepository dataMining incidental dataDrawing conclusions

FreeBSDComplete operating systemOpen sourceHigh performance application serversNetworked embedded systemsDerived from BSD UnixFocus on stability and reliabilitysmallbusiness.yahoo.comPart of Apples Mac OS X

Family Tree

Development~350 developers

DocumentationThird party application ports~15700Operating system utilities~9.8MLoCKernel~3.8MLoCDocumentation

Development FacilitiesCVS (12 years of historical data; >938k)Problem reports (>95k)Mailing lists (>100)TinderboxWeb siteDevelopers handbookRelease engineeringBrowsable CVSMailing listsPRs

Development ProcessUnpaid volunteersTeamsCoreRelease engineeringSecurityPortsDonationsCommitter etiquetteMentoring

Global Development

Around the Globe

Division of Work

Chart9

37.022

144.397

145.161

1793.869

2527.855

6.373

KLoC

KLoC

Sheet1

MainBranch

Africa2194715075

Asia10130243095

Australia13377811383

Europe1283063510806

North America14144771113378

South America48531520

KLoCMainBranch

Africa372215

Asia14410143

Australia14513411

Europe17941283511

North America252814141113

South America652

Sheet1

Branch

Main

KLoC

Work type per area

Sheet2

KLoC

KLoC

Sheet3

wwwsrcdocports

Africa11237022158525868

Asia2183914439774938786213

Europe10871817938691347701690072

SouthAmerica25363732028145150

NorthAmerica464492527855328491827419

Australia42214516151494514

wwwsrcdocports

Africa037226

Asia2214475786

Europe10917941351690

South America062145

North America462528331827

Australia0145195

Sheet3

src

www

doc

ports

Work type per area

Hold and Advance

Chart11

15.07521.947

43.095101.302

11.383133.778

510.8061283.063

1113.3781414.477

1.524.853

Branch

Main

KLoC

Work type per area

Sheet1

MainBranch

Africa2194715075

Asia10130243095

Australia13377811383

Europe1283063510806

North America14144771113378

South America48531520

KLoCMainBranch

Africa372215

Asia14410143

Australia14513411

Europe17941283511

North America252814141113

South America652

Sheet1

Branch

Main

KLoC

Work type per area

Sheet2

KLoC

KLoC

Sheet3

wwwsrcdocports

Africa11237022158525868

Asia2183914439774938786213

Europe10871817938691347701690072

SouthAmerica25363732028145150

NorthAmerica464492527855328491827419

Australia42214516151494514

wwwsrcdocports

Africa037226

Asia2214475786

Europe10917941351690

South America062145

North America462528331827

Australia0145195

Sheet3

src

www

doc

ports

Work type per area

and FixClosed GNATS entries per area

Chart7

1.28443

12.6661

40.5642

2.34077

35.9055

7.23898

work

MainBranch

Africa2194715075

Asia10130243095

Australia13377811383

Europe1283063510806

North America14144771113378

South America48531520

KLoCMainBranch

Africa372215

Asia14410143

Australia14513411

Europe17941283511

North America252814141113

South America652

work

Branch

Main

KLoC

Work type per area

distribution

KLoC

KLoC

passing work

wwwsrcdocports

Africa11237022158525868

Asia2183914439774938786213

Europe10871817938691347701690072

SouthAmerica25363732028145150

NorthAmerica464492527855328491827419

Australia42214516151494514

wwwsrcdocports

Africa037226

Asia2214475786

Europe10917941351690

South America062145

North America462528331827

Australia0145195

Africa1.28443901

Asia12.66618885

Europe40.564228455

South America2.340771642

North America35.905525187

Australia7.238985078

passing work

src

www

doc

ports

Work type per area

Commit days>8h by different committers>8h same committersNext day commits

Files11.04290.119160.1966640.374491

Modules117.03414.65036.0069221.0038

All4467428222394367

>8h by different committers>8h by the same committerNext day commits

Files1.08%1.78%3.39%

Modules12.52%5.13%17.95%

All95.86%50.12%97.76%

>8h by different committers

>8h by the same committer

Next day commits

Granule

Days

Roads and Buildings

Chart6

37.0220.1121.58525.868

144.39721.83974.938786.213

1793.869108.718134.771690.072

6.3730.2532.028145.15

2527.85546.44932.8491827.419

145.1610.4220.51494.514

src

www

doc

ports

Work type per area

Sheet1

MainBranch

Africa2194715075

Asia10130243095

Australia13377811383

Europe1283063510806

North America14144771113378

South America48531520

MainBranch

Africa2215

Asia10143

Australia13411

Europe1283511

North America14141113

South America52

Sheet1

Branch

Main

KLoC

Development per area

Sheet2

wwwsrcdocports

Africa11237022158525868

Asia2183914439774938786213

Europe10871817938691347701690072

SouthAmerica25363732028145150

NorthAmerica464492527855328491827419

Australia42214516151494514

wwwsrcdocports

Africa037226

Asia2214475786

Europe10917941351690

South America062145

North America462528331827

Australia0145195

Sheet2

src

www

doc

ports

Work type per area

Sheet3

Round the Clock

Passing Work Around

Chart6

0.01079064380.017809090.0339123781

0.12517986230.05132628130.1794675052

0.95858518020.50123125140.9776136109

>8h by different committers

>8h by the same committer

Next day commits

Granule

Days

work

MainBranch

Africa2194715075

Asia10130243095

Australia13377811383

Europe1283063510806

North America14144771113378

South America48531520

KLoCMainBranch

Africa372215

Asia14410143

Australia14513411

Europe17941283511

North America252814141113

South America652

work

Branch

Main

KLoC

Work type per area

distribution

KLoC

KLoC

passing work

wwwsrcdocports

Africa11237022158525868

Asia2183914439774938786213

Europe10871817938691347701690072

SouthAmerica25363732028145150

NorthAmerica464492527855328491827419

Australia42214516151494514

wwwsrcdocports

Africa037226

Asia2214475786

Europe10917941351690

South America062145

North America462528331827

Australia0145195

Africa1.28443901

Asia12.66618885

Europe40.564228455

South America2.340771642

North America35.905525187

Australia7.238985078

passing work

src

www

doc

ports

Work type per area

Commit days>8h by different committers>8h same committersNext day commits

Files11.04290.119160.1966640.374491

Modules117.03414.65036.0069221.0038

All4467428222394367

>8h by different committers>8h by the same committerNext day commits

Files1.08%1.78%3.39%

Modules12.52%5.13%17.95%

All95.86%50.12%97.76%

>8h by different committers

>8h by the same committer

Next day commits

Granule

Days

Productivity and QualityRound the clock developmentSoftware and hardware diversityLack of face-to-face communicationAsynchronous communicationA more rigorous process is requiredCultural diversity

ProductivityMore developers produce more software (base case) r=0.67 (95% CI)

Productivity but developer distance doesnt affect productivity. r=-0.14 (95% CI)

Code Style r=0.05 (95% CI)

Defect Density r=0.07 (95% CI)

Human InteractionsLook for neighborsCooperating developersMentors and menteesJan Van Haasteren: Neighbours

Cooperating developersMean distance betweenany two FreeBSD developers: 6,701km4010 instances of commitsSame fileSame dayDifferent developersMean distance: 6,489km

Mentors and mentees

MinMedianMeanMaxAny02.27.86.79.319M/M00.73.85.08.818

FreeBSD is GlobalRound the clock developmentNo ill effects onProductivityCode qualityBug densityDistanceDoesnt show up in ad hoc cooperationAppears to matter in mentoring

Tesekur Ederim!

http://www.freebsd.orghttp:/www.dmst.aueb.gr/dds