Optimizing Ruby Path Methods | byroot’s blog

Back in November last year, I started a new job at Intercom, and one of the first projects I got to work on was improving the Intercom monolith CI with some of my new colleagues. Interestingly, I never got around to talking about CI on this blog, even though I consider it to be one of my main areas of expertise. That topic is way beyond the subject I’d like to talk about here, but just to give a bit of context, a key driver in CI performance and user experience is how fast you can get a Ruby process ready to run tests. When working with very large test suites, it becomes essential to run tests in parallel. If you have a test suite that runs in say, 1 hour, on paper, you can run it in 15 minutes on 4 workers, or in 6 minutes on 10 workers, and 1 minute on 60 workers.