Thanks for the insights,
The reason I ask about this semaphore pattern is id like to assign parties to role groups. There has been a few threads on this
For example, my app is a phone book with 1000+ pages.
Lets assume its hosted on DABL so if it takes off everyone is their own unique party. I don’t know of a nice way to group N parties to 1 group type role without experiencing this phenomena I am coining the observer propagation quandary TM 
A newly onboarded party is a basic user by default, I need to give them the ability to fetch every phone book page so my goal is to make them a stakeholder of all 1000+ phone book pages.
To achieve this, I need to do a bulk update and propagate this newly onboarded user to the observer list of all 1000+ phone book pages. (This is the part I am concerned over and if there needs to be some form of global lock in place).
I have other specific roles but these arent an issue because I have single role contracts for individual parties so they can do role membership checks by simple lookupByKey which I really like.
Is there a solution to this quandary or something to make me feel at ease that I am not doing something really dodgy?