Can you point to a concrete example of the "scheduler" pattern you're referring to? I'm not familiar with it, and it's not clear to me from your post how it works.
I might be wrong but I suspect the "schedular" in this instance is the thing granting write access.
Consider a SQL database engine.
Many threads/process can be accessing a SQL database at any given time.
But if two of those actors require write access to a same object, only one will be allowed access and all others are blocked.
So at this high level the concurrency is guaranteed by the engine, which then means at the low level the engine can safely assume the access is exclusive.
Consider a SQL database engine.
Many threads/process can be accessing a SQL database at any given time.
But if two of those actors require write access to a same object, only one will be allowed access and all others are blocked.
So at this high level the concurrency is guaranteed by the engine, which then means at the low level the engine can safely assume the access is exclusive.