Where does it say that?

It says things like:

“We were not creating a lot of garbage.”

... but that statement there doesn’t say anything about the heap size, including the size and count of live objects (i.e., not garbage).

It also says:

“There are millions of Users in each cache. There are tens of millions of Read States in each cache.”

Large is often in the eye of the beholder, but I missed it if it said anything specifically about not having a large heap size.

> ... but that statement there doesn’t say anything about the heap size, including the size and count of live objects (i.e., not garbage).

Not sure why you got downvoted, you're actually right, I'm wrong: I misread that and/or assumed one meant the other.

That said, this is a case that should be ideal for generational GC, which Go specifically eschewed at one point. I'm not sure this is still the case, however--I have yet to wade through this[1] to update my knowledge here.

[1] https://blog.golang.org/ismmkeynote