The connection between Hypercorn and a client can be paused by either party to allow that party time to process the information it has received, i.e. to catch up. When the connection is paused the sender effectively receives pressure to stop sending data. This is commonly termed back pressure.
Hypercorn will respond to client backpressure by pausing the sending
of data. This back pressure will propogate back to any ASGI framework
via a blocked (without blocking the event loop) ASGI send
awaitable. In other words any
await send(message) calls will block
the coroutine till the client backpressure has abated or the
connection is closed.