HTTP/2

Overview

HTTP/2.0 is the latest version of the HTTP protocol. It improves significantly upon HTTP/1. Most importantly, it introduces a binary wire protocol with multiplexed streams over a single TCP connection. This solves a long-standing performance issue with HTTP/1.1: head-of-line blocking.

Well, it at least partially solves it. The TCP congestion control mechanisms can interfere with the intended independent nature of the multiplexed streams in cases of lost/dropped packets and retransmission/reassembly. The full solution is to run HTTP/2.0 over UDP, as Google implemented with QUIC.

Additional features of HTTP/2.0

Builtin compression of HTTP headers
Server push
Pipelining of requests
Prioritization of requests

Load testing HTTP/2 with k6

When you make HTTP requests in k6, k6 automatically upgrades the connection to HTTP/2.0 if the server supports it, just like your web browser would.

To check what protocol was used for a particular request, refer to the proto property of the response object.

import http from 'k6/http';
import { check, sleep } from 'k6';

export default function () {
  const res = http.get('https://test-api.k6.io/');
  check(res, {
    'protocol is HTTP/2': (r) => r.proto === 'HTTP/2.0',
  });
  sleep(1);
}

To see the values that the r.proto field can have, refer to the documentation for k6 HTTP.