It’s notoriously hard to measure the usage of open-source software. Software that’s open-source or free can be redistributed far and wide, so the original creators have no idea how many times it’s installed, deployed, or distributed. As a proxy, we often use downloads, but that’s woefully inadequate.
I’ve recently begun trying to figure out how many job openings are mentioning various open-source projects. I think that this might be a better metric because it’s driven by the end result (usage), rather than intermediate processes (downloads, etc). I think that it’s likely that usage and demand for skilled people is somewhat realistically related.
To be more concrete, I’ve been watching RSS feeds from job posting aggregators for several alternative versions of MySQL: Percona Server, MariaDB, and Drizzle. It appears that Percona Server is by far the most in-demand in terms of job skills. (I haven’t seen a job posting for the others at all, so far.)
On the other hand, my sample is skewed; I think Percona Server is better known in America, but MariaDB might be more visible in Europe. And I’m not sure that the sample data set is large enough to be statistically significant. Percona Server jobs are utterly dwarfed by MySQL jobs.
There are other flaws in my method: some software doesn’t really need as much manpower to run as others. I would say that given an equal number of WordPress and Drupal websites, more of the Drupal websites are going to be trying to hire experts to manage their sites. So nothing is apples to apples.
What do you think about this metric and its merits or drawbacks? Is there a better way to figure out how much adoption a project really has?