You may have missed the "multi threaded vs single threaded" section where they talk about a very similar pattern: "The way it works is simple, it uses blocking

You may have missed the "multi threaded vs single threaded" section where they talk about a very similar pattern: "The way it works is simple, it uses blocking IO, but each blocking call is made in its own thread. Now depending on the implementation, it either takes a callback, or uses a polling model, like returning a Future."