Migration patterns of open source ecosystem contributors - An empirical case study with GNOME

Migration patterns of software ecosystem contributorsAn empirical case study with Gnome

T. Mens, M. Claes, M. Goeminne

Software Engineering Lab, Computer Science DepartmentFaculty of Science, University of Mons

SOS-Evol 2013

Research context The Gnome ecosystem Migration patterns Conclusion

1 Research context

2 The Gnome ecosystem

3 Migration patterns

4 Conclusion

T. Mens, M. Claes, M. Goeminne (Genie Logiciel)Migration patterns of software ecosystem contributors SOS-Evol 2013 2 / 26


ARC interdisciplinary research project ECOS

“Ecological Studies of Open Source Software Ecosystems”

Rely on ecological models and theories of the evolution of biologicalecosystems

Adapt and adopt these theories to study the evolution of OSSecosystems

Understand, and provide support for, optimizing the fitness, resistanceand resilience of OSS projects within their ecosystem



Biological ecosystem



1 Research context



4 Conclusion



About Gnome

16 years of history (1997 to 2012)

1,418 projects (stored in git version repositories)

1,315,997 commits

12,285,518 file touches

11,094 identities before merging; 5,923 after identity merging

open source (of course)

actively studied by many researchers



Database Schema

FLOSS-compliant, extension of CVSAnaly2



Some empirical results on Gnome

Evolution of active contributors and active projects



Some empirical results on Gnome - 2

Correlations between some Gnome ecosystem metrics




Code commits and code touches

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code_touches"




No correlation between code commits and code touches

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correla'on)code_commits)code_touches)



1 Research context



4 Conclusion



Migration patterns

How do contributors join, leave and move across projects of theecosystem?

Which migration patterns can we observe?

Do joiners of a project come from other projects or from outside theecosystem?Do project leavers tend to stay within other projects of the ecosystem?Does the migration pattern change over time?Do some projects attract or loose more contributors than others?



Metrics definitions

DevP (t) = {contributors ∈ P who made at least two code commits during period t}

stayersS (t) = |{a|∃P1 ∈ S, a ∈ DevP (t − 1) ∧ ∃P2 ∈ S, a ∈ DevP (t)}|

joinGlobalS (t) = |{a|∃P ∈ S, a ∈ DevP (t) ∧ ∀P ∈ G , a 6∈ DevP (t − 1)}|joinLocalS (t) = |{a|∃P ∈ S, a ∈ DevP (t) ∧ ∀P ∈ S, a 6∈ DevP (t − 1) ∧ ∃P ∈ G , a ∈ DevP (t − 1)}|joinersS (t) = joinGlobalS (t) + joinLocalS (t)

leaveGlobalS (t) = |{a|∃P ∈ S, a ∈ DevP (t − 1) ∧ ∀P ∈ G , a 6∈ DevP (t)}|leaveLocalS (t) = |{a|∃P ∈ S, a ∈ DevP (t − 1) ∧ ∀P ∈ S, a 6∈ DevP (t) ∧ ∃P ∈ G , a ∈ DevP (t)}|leaversS (t) = leaveGlobalS (t) + leaveLocalS (t)



Analysis results - Joiners, leavers & stayers

Glib

Increasing trend in joiners, leavers & stayers




GIMP

Stable trend in joiners, leavers & stayers




Gnumeric

Initial “phase” and stable trend phase in joiners, leavers & stayers




Gnome-applets

High variation of leavers/joiners & decreasing trend




GDK Pixbuf

High peak of death...?



Analysis results - Local vs. global for joiners & leavers

Glib

Wilcoxon signed rank test

Hypothesis 1: joinGlobal < joinLocal (p-value: 4.175e−6)

Hypothesis 2: leaveGlobal < leaveLocal (p-value: 5.279e−6)




GIMP

Wilcoxon signed rank test

Hypothesis 1: joinGlobal > joinLocal (p-value: 9.361e−6)

Hypothesis 2: leaveGlobal > leaveLocal (p-value: 1.243e−4)




Gnumeric

Wilcoxon signed rank test unconclusive (p-values: 0.339 & 0.8415)



1 Research context



4 Conclusion



Conclusion

Empirical results on Gnome

Huge increase of contributors around 2008Huge decrease of code touches around 2002

Gnome migrations

Different patternsProjects (like libraries): peripheral developers (joiners and leavers) tendto be contributors from other GNOME projectsProjects (like GIMP) attracting people outside Gnome⇒ famous Gnome’s projects?



Many future works

Apply this analysis more in depth to a broader set of projects

Where do developers come when a new project has been started?

Developer’s point of view:

Where do they come from?Where do they go?Which motivation?

⇒ dual study of migrations

Project stability?

Carry out the study at different levels: individual projects,sub-ecosystems, entire ecosystem

Social or socio-technical analysis of Gnome

Mass migrations

Other ecosystems...



Thanks for your attention!

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Migration patterns of open source ecosystem contributors - An empirical case study with GNOME