I noticed that while compiling an application, ParallelCompiler will compile multiple modules in parallel, as long as the dependencies between them allow this, but that compiling mix dependencies does not. It compiles each package one-by-one. While some packages really take advantage of all cores, others do not, and I wonder if there are any constraints that prevent Elixir from monitoring parallelism within a package and if it’s making proper use of all cores.

I imagine that compiling all dependencies could be a multi-step process, first scanning and sorting by dependency on others, and then, similar to GenStage and Flow, dispatch modules to be compiled as events to System.schedulers_online, making sure that each consumer is compiling at least one module.

I’m looking to hear other people’s thoughts on this, as well as seeing how your dependency compilation times and cpu usage compare (time mix deps.compile --force), and if they are making optimal use of all your cores.

My result:
MacBook Pro 2019, 2.4GHz 8 core i9: mix deps.compile --force 231.52s user 25.97s system 317% cpu 1:21.12 total