Https://Github.Com/Hyperium/Tonic/Blob/Master/Examples/Src/Routeguide/Server.Rs#L51 async fn list_features(

Question

Https://Github.Com/Hyperium/Tonic/Blob/Master/Examples/Src/Routeguide/Server.Rs#L51 async fn list_features(

&self,
request: Request<Rectangle>,
) -> Result<Response<Self::ListFeaturesStream>, Status> {
println!("ListFeatures = {:?}", request);

let (tx, rx) = mpsc::channel(4);
let features = self.features.clone();

tokio::spawn(async move {
for feature in &features[..] {
if in_range(feature.location.as_ref().unwrap(), request.get_ref()) {
println!(" => send {:?}", feature);
tx.send(Ok(feature.clone())).await.unwrap();
}
}

println!(" /// done sending");
});

Ok(Response::new(ReceiverStream::new(rx)))
}

зачем итерация и отправка в канал идут в отдельном потоке?