In systemd's case, it is. Everything is buried through layers of obscure abstraction, and understanding the code can be a difficult task, indeed. On the other

In systemd's case, it is. Everything is buried through layers of obscure abstraction, and understanding the code can be a difficult task, indeed. On the other hand, Upstart makes heavy use of libnih (it's like glib, but nowhere near as heavy) and is actually very easy to follow. Compared to systemd, it certainly is, at least. Many of the comments are actually annotations for the automated documentation generator, from what I recall. OpenRC makes use of source code comments in a more conventional way, but they actually do tend to help with adding insight into what was going on in the author's head, and the code is still understandable (though not as clean as Upstart's), regardless. Its small size obviously also helps.