Upstart doesn&#x27;t have a formal dependency system, instead it orders things based on named preconditions and postconditions called events. Though these can be used to fulfill ordering requirements, I&#x27;d wager the information wasn&#x27;t granular enough for parallelization to be efficient.<p>Actually the main problem is that a lot of modern systems do not make their dependency graphs well observable, but instead treat them as in-memory ephemera that are constantly recalculated and cannot e.g. be written to persistent storage as known-good checkpoints.<p>This is one area where s6-rc gets it right. You have to compile a manifest of your service dependencies and consistently boot from that well-known state, so for any changes it must be regenerated.<p>serel was an earlier example of a service dependency system and parallel launcher which directly had you specify the nodes and edges of a directed graph as an RDF manifest. Clever.