Demographics of Linux kernel developers: how old are they?

Talk at SOS-Evol 2013. The Linux kernel git repository hosts several years of activity. We have analyzed it with the aim to learn about the "age" structure of the community of developers, and how it has evolved over time. After looking at the commit activity by each of them, periods of stay and leave have been determined, and later used to draw demographics pyramids, with time of stay in the project as "age". The analysis of such pyramids and related parameters help to better understand the experience of the community of developers, how new people is entering the project, and some bounds on the future evolution. We propose this analysis on the Linux kernel as a case study of a methodology that could be used to study many other development communities.

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1. Demographics of Linux kernel developers how old are they? (work in progress) Jesus M. Gonzalez-Barahona jgb@bitergia.com http://identi.ca/jgbarah http://twitter.com/jgbarah Bitergia GSyC/LibreSoft (Universidad Rey Juan Carlos) SOS-Evol, Brussels, February 1st, 2013 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 1 / 20
2. c 2013 Bitergia Some rights reserved. This presentation is distributed under the “Attribution-ShareAlike 3.0” license, by Creative Commons, available at http://creativecommons.org/licenses/by-sa/3.0/ Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 2 / 20
3. Approach General question: “Can we learn about sustainability by looking at the history?” Specific question: “Can we characterize the evolution of the development community by looking at the git repository?” Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 3 / 20
4. The Linux kernel case large project large community migrated to git on 2005 (about 8 years of history) How much “new blood” is entering the project? How many “old people” are retiring? Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 4 / 20
5. Methodology Get git commit records into a database (CVSAnalY) Find out unique developers (merge developers with several identities) For several moments (yearly) in the history of the project: We consider “time in project” as “age” Calculate and plot demographic pyramid Generations calculated as “entered in the same period” Periods are of three months Analyze results Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 5 / 20
6. Methodology (unique developers) Identities as “Name” (name), “email address” (eaddress) Remove “???”, “” , etc. Duplicates: Name in eaddress (probably name is an email address) Email address in eaddress (same eadress, different names) From 9,952 entries to 9,101 “unique” developers (seems good enough, by manual inspection of random sample) Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 6 / 20
7. Methodology (finding intervals) SELECT upeople.uid as id, people.name as name, MIN(scmlog.date) as firstdatestr, MAX(scmlog.date) as lastdatestr FROM scmlog, people, upeople where scmlog.author_id = upeople.id AND people.id = upeople.id group by upeople.uid" Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 7 / 20
8. October 2007 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 8 / 20
9. October 2008 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 9 / 20
10. October 2009 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 10 / 20
11. October 2010 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 11 / 20
12. October 2011 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 12 / 20
13. October 2012 Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 13 / 20
14. All together (dodged) Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 14 / 20
15. All together (faceted) Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 15 / 20
16. All together (superposed) Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 16 / 20
17. Conclusions Generations are smaller and smaller from about 100-150 to 30-50 per quarter Older generations are disappearing Last generations quite smaller now than they were six years ago Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 17 / 20
18. Conclusions Does this mean something? (This is still work in progress) Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 18 / 20
19. Bitergia: a start-up on free software metrics Started operations in July 2012 Builds on the experience of LibreSoft R&D group Offering professional products and services Focused on: Metrics about software developent (including community metrics) Specialized support for development forges (including metrics for projects) http://bitergia.com http://blog.bitergia.com http://libresoft.es Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 19 / 20
20. This is the end Have you learned something useful? [I would love to know what interested you the most] [...and the least] Jesus Gonzalez-Barahona (Bitergia) Demographics of Linux kernel developers SOS-Evol 2013 20 / 20