Should apps orchestrate a super-global lock of a foreign namespace?

An environment variable's value, for a running process, is just what it is: an initial value from outside.

Adding complexity around it smells like an attempt to control a distributed mutex, like checking an API for real-time value changes in a while loop across several instances of the same app.

I thought there would be alternatives to this, like pubsub, Kafka, or other asynchronous event handling.

Imagine having to test an app for its ability to handle safe read-write of OS-level state. It's definitionally bankrupt: not really a unit, not easy to set up quickly, and not isolated.