2017 is coming to a close, and unless someone commits something very soon, WordPress Core development is at rest (since we have an API to do that now). This is the third year I've compiled these stats, see the 2016 committer stats for some of the background information. I'm going to share the stats and then share my reactions to seeing them.
An important caveat, in the post I'll mention employers but we need to remember that people change jobs and that not everyone works on donated time. In fact, the vast majority of WordPress core committers are volunteering their time when they review, write, and commit code to WordPress.
2017 will end the year with 1731 changesets to trunk. This is down from 2967 last year. These changesets were committed by 35 individuals, down from 37 in 2016.
2017's most prolific committer was Sergey Biryukov who was responsible for 20.57% of all WordPress commits. He takes this crown from Dominik Schilling. In raw numbers, Dominick had 4 more commits in 2016 than Sergey did in 2017. This is the first time since I started keeping these stats that a non-release lead has had the lead.
Other notable committers (by volume of commits) in 2017 were Weston Ruter (18.14%) and John Billion (11.84%).
The employer who was most responsible for WordPress commits this year was Yoast with 24.67%. 14 different employers (grouping all the self-employed individuals into a single group for this purpose). This is down from 20. In 2016, Automattic was first with 14.66%.
Thoughts and Reactions
The number of higher volume committers is down substantially. In 2016, 17 had at least 52 commits, in 2017 it was 11. Only 3 individuals had over 100 commits in 2017, while in 2016 it was 11.
The number of core commits and committers continues to fall, but that's in part due to projects like the rest- and Gutenberg being developed outside of Trac. If WordPress continues to move away from the monolithic repo model, I think this trend will continue. Additionally, with only 2 major releases and no new default theme, there was less to do in (and many people that were active in Core development have devoted themselves to Gutenberg, the new hosting team, and other WordPress efforts).
I also don't think that it can be ruled out that as a complex piece of software with moderate (at best) automated test coverage, people tend to be cautious and risk-averse. Increasing the automated test coverage should help with these efforts.
Finally, WordPress does continue to improve. It had two major releases in 2017 bringing some long requested changes to a large swath of the internet. Commit numbers is far from a perfect metric. Some people it takes one commit to get right, sometimes it takes 3 commits to not break the build when landing something. Looking at it and watching it in context of everything else, we can see that WordPress is for an incredible 2018.