Every so often, a thread shows up on the golang-nuts asking for some form of
goroutine-local-storage, or some kind of goroutine id, or some kind of context.
There are a few valid use cases for goroutine-local-storage, one of the most
prominent being log line context. One poster was interested in being able to
log an HTTP request context id in every log line in the same goroutine as the
incoming HTTP request, without having to change every library and function call
he was interested in logging.

It is my duty to point you to https://blog.golang.org/context, which is how
Google solves all of the problems you'd perhaps consider using this package for
at scale.