3 ms·

> Long-Polling: The least scalable due to the high server load generated by frequent connection establishment, making it suitable only as a fallback mechanism.

• hnav 3y ago
  there are a few ways that long-polling is "least scalable" - other approaches give you locality without sticky load-balancing: let's say your application server needs to subscribe to a topic once a connection is established, with long polling you need to setup and teardown that subscription every time, other approaches let you keep that HTTP stream alive and periodically send some stuff on it resulting in mostly just memory overhead. - each returned payload will result in at least 1 extra packet (the initial request headers, assuming the response headers and the payload fit into a packet) and at least 1/2 RTT delay.