halting problem :: Who wrote GTK+ 3.18

:: ~8 min read

This may be a recurring series at the end of each development cycle, to sum up who worked on the core of the GNOME platform. Matthias is very good at blogging about the changes in GTK, with lots of screenshots, but I want to concentrate on who contributed what, in the spirit of the LWN series on the Linux kernel.

It’s common “knowledge” in the Internet Peanut Gallery that GTK+ is “dead” or “dying” — I assume in the same sense that NetCraft certified that BSD is dead. It’d be (and, in point of fact, it is) easy to dismiss these rumors; it’s not like they come with actual numbers and trends, because the gods of old never mentioned the requirement for comments on the Internet to be cogent, let alone factually true, when they laid down the various RFCs.

On the other hand, not having an actual answer is a bit of a self-serving argument on the side of people, like me, that actually contribute to GTK+ and to the GNOME core platform; it allows a bit of leeway when we ask for help, contributions, or simply for decent bug reports — “we don’t have enough resources, so if you want your pet bug fixed, or feature implemented, you’ll have to help us help you”. Not that having actual numbers would change that; after all, resources are not infinite, and there are a ton of bugs that need to be fixed — including ones that require a time machine.

As much as I wanted to dispel the rumors about the impending death of GTK+, my goal was definitely to provide numbers on how much gets done every six months in the core GNOME platform, thus honoring the people that work hard on it. Having numbers also allows us to quantify what kind of help we need, so that, the next time somebody complains that we don’t work hard enough on fixing ALL the bugs, at least we’ll have a handy way to point out how much we work already.

To gather the data, I’ve used the most excellent git-dm tool that Jonathan Corbet wrote for the “Who wrote the Linux kernel” columns for LWN.


To provide a baseline, this is how the development activity looked like during the GNOME 3.14 and 3.16 cycles, i.e. during the past year:

Version Lines added Lines removed Delta Contributors
GLib 2.42 17195 9934 7261 61
GLib 2.44 12504 2240 10264 49
GTK+ 3.14 130387 144945 -14558 84
GTK+ 3.16 80321 37043 43278 94

Note: the numbers do not include the translation work; as much as translations are an important part of our stack, they tend to skew any statistic, given the sheer size of lines touched.

The 3.14 cycle is an outlier for GTK+ because of the move of Adwaita in tree, as well as the GTK+ Inspector.

For the 3.18 cycle, the numbers up to September 15th are:

Version Lines added Lines removed Delta Contributors
GLib 2.46 19763 12437 7326 50
GTK+ 3.18 78676 54508 24168 83

As you can see, the numbers are mostly stable, in terms for code changes and number of developers.


Of the 50 developers that contributed the 355 changesets of GLib during the 3.18 cycle, the most active are:

Name Per changeset Name Per changed lines
Matthias Clasen 89 (25.9%) Руслан Ижбулатов 7337 (27.6%)
Philip Withnall 50 (14.5%) Ryan Lortie 5709 (21.5%)
Ryan Lortie 31 (9.0%) Chun-wei Fan 3426 (12.9%)
Dan Winship 29 (8.4%) Matthias Clasen 2881 (10.8%)
Simon McVittie 19 (5.5%) Philip Withnall 1729 (6.5%)
Chun-wei Fan 14 (4.1%) Dan Winship 1590 (6.0%)
Руслан Ижбулатов 11 (3.2%) Simon McVittie 867 (3.3%)
Mikhail Zabaluev 8 (2.3%) Alexander Larsson 648 (2.4%)
Ting-Wei Lan 8 (2.3%) Paolo Borelli 588 (2.2%)
Garrett Regier 6 (1.7%) Patrick Griffis 358 (1.3%)
Alexander Larsson 5 (1.5%) Janusz Lewandowski 313 (1.2%)
Michael Catanzaro 5 (1.5%) Mikhail Zabaluev 256 (1.0%)
Emmanuele Bassi 5 (1.5%) Iain Lane 130 (0.5%)
Christophe Fergeau 5 (1.5%) Garrett Regier 128 (0.5%)
Paolo Borelli 5 (1.5%) Michael Catanzaro 106 (0.4%)
Piotr Drąg 4 (1.2%) Richard Hughes 97 (0.4%)
Kalev Lember 4 (1.2%) Emmanuele Bassi 70 (0.3%)
Iain Lane 4 (1.2%) Xavier Claessens 48 (0.2%)
Patrick Griffis 4 (1.2%) Ross Lagerwall 35 (0.1%)
Rico Tzschichholz 3 (0.9%) Ting-Wei Lan 32 (0.1%)

Руслан Ижбулатов has been working on the Windows support, ensuring that the library and test suites work correctly there. Chun-wei Fan has been fixing the project files for building GLib (and GTK+, as well as a lot of libraries in the GNOME stack) with Microsoft Visual Studio and the Microsoft Visual C Compiler. Philip Withnall has been hard at work on the API reference and GObject tutorial, incorporating the feedback he got from clients at Collabora. Dan Winship and Michael Catanzaro have been working on the certificate API inside GIO, even though the bulk of the work has been going on inside the external glib-networking module. Simon McVittie has been working on GDBus; on the testing API; and has been incorporating patches coming from the Debian project.

For GTK+, on the other hand, the most active of the 83 contributors are:

Name Per changeset Name Per changed lines
Matthias Clasen 811 (49.8%) Matthias Clasen 37393 (37.3%)
Benjamin Otte 184 (11.3%) Chun-wei Fan 22644 (22.6%)
Carlos Garnacho 107 (6.6%) Benjamin Otte 10991 (11.0%)
Cosimo Cecchi 40 (2.5%) Jakub Steiner 4762 (4.7%)
Jakub Steiner 37 (2.3%) Georges Basile Stavracas Neto 3879 (3.9%)
Lapo Calamandrei 35 (2.1%) Carlos Soriano 3827 (3.8%)
Emmanuele Bassi 33 (2.0%) Lapo Calamandrei 3208 (3.2%)
Carlos Soriano 30 (1.8%) Carlos Garnacho 2690 (2.7%)
Timm Bäder 29 (1.8%) Руслан Ижбулатов 1480 (1.5%)
Chun-wei Fan 24 (1.5%) Alexander Larsson 1001 (1.0%)
William Hua 24 (1.5%) William Hua 947 (0.9%)
Alexander Larsson 23 (1.4%) Cosimo Cecchi 704 (0.7%)
Georges Basile Stavracas Neto 23 (1.4%) Paolo Borelli 671 (0.7%)
Jonas Ådahl 19 (1.2%) Jasper St. Pierre 627 (0.6%)
Christian Hergert 17 (1.0%) Christian Hergert 592 (0.6%)
Piotr Drąg 17 (1.0%) Sebastien Lafargue 570 (0.6%)
Paolo Borelli 17 (1.0%) Emmanuele Bassi 556 (0.6%)
Christoph Reiter 14 (0.9%) Jonas Ådahl 543 (0.5%)
Руслан Ижбулатов 13 (0.8%) Christoph Reiter 488 (0.5%)
Jasper St. Pierre 11 (0.7%) Ryan Lortie 424 (0.4%)

While Benjamin is hard at work at improving the correctness and performance of the style machinery inside GTK+, Jakub and Lapo are constantly trying to find ways to make Adwaita and the High Constrast themes push the boundaries of the same style machinery. Carlos Soriano and Georges Basile Stavracas Neto have been working on the components of the file selection dialog following the new designs from Allan Day, for the Google Summer of Code; the code is going to be shared between GTK+ and Nautilus, to improve consistency between Nautilus and the GtkFileChooser widget, and keep bugs to a minimum. Carlos Garnacho has worked on input — mostly the support for touchpad on Wayland. Also on Wayland, Jonas Ådahl has been working on bug fixing and feature parity in GDK between Wayland and X11.

From a company perspective, Red Hat still dominates, as it employs many of the more prolific contributors; nevertheless, it’s important to note that a larger number of developers are unaffiliated, or contribute to GLib and GTK+ in their own time:


Affiliation Per changeset Affiliation Per lines Affiliation Per contributor (total 52)
Red Hat 138 (40.1%) (Unknown) 12892 (48.5%) (Unknown) 32 (61.5%)
(Unknown) 95 (27.6%) Canonical 5794 (21.8%) Red Hat 10 (19.2%)
Collabora 65 (18.9%) Red Hat 5222 (19.6%) Canonical 3 (5.8%)
Canonical 37 (10.8%) Collabora 2574 (9.7%) Collabora 2 (3.8%)
Endless 6 (1.7%) Endless 72 (0.3%) Endless 2 (3.8%)
Centricular 2 (0.6%) Centricular 28 (0.1%) Centricular 2 (3.8%)


Affiliation Per changeset Affiliation Per lines Affiliation Per contributor (total 85)
Red Hat 1230 (75.5%) Red Hat 61725 (61.6%) (Unknown) 58 (68.2%)
(Unknown) 340 (20.9%) (Unknown) 36845 (36.7%) Red Hat 19 (22.4%)
Endless 43 (2.6%) Endless 1181 (1.2%) Canonical 3 (3.5%)
Canonical 13 (0.8%) Canonical 491 (0.5%) Endless 2 (2.4%)
Collabora 2 (0.1%) Collabora 19 (0.0%) Collabora 2 (2.4%)
Intel 1 (0.1%) Intel 2 (0.0%) Intel 1 (1.2%)


One of the most obvious conclusions that I can draw from these numbers is that GLib and GTK+ are definitely capable of retaining existing contributors — you just need to look at the names in the top committers and check how many GUADECs they have attended; what’s less obvious is the capacity of acquiring and retaining new contributors. For the latter, the Summer of Code and Outreachy programs are definitely a great resource. Carlos and Georges have been working their way down the stack at an impressive speed, and are now responsible for core functionality.

In terms of contributions, I think the code base has long since reached a point where it cannot be increased without also increasing the number of stable contributors. This is not a bad thing, per se; GLib and GTK+ are not the Linux kernel; we cannot add widgets like the kernel adds drivers, or file systems. It is mostly clear, though, that new functionality must come with new people that take responsibility for it, or at the expense of deprecating old API.

glib gtk development gnome who makes gnome