The Unpredictable Stock Service: Code

import Fastify from "fastify";

const app = Fastify();

app.get("/stock", function (request, reply) {
	const stock = [
		{ id: "cf93d53f-7f60-4c9d-a543-ef217a09269b", name: "Cookies 'n' Cream", stock: 8532 },
		{ id: "41373bb6-e6fb-4606-8f01-1cd24e228939", name: "Neopolitan", stock: 0 },
		{ id: "8e884a8d-ae04-4518-80b7-377ee5bcecc6", name: "Pistachio", stock: 6437 }
	];

	const delay = Math.floor(Math.random() * 10000);

	setTimeout(() => {
		reply.send({ stock, delay });
	}, delay);
});

await app.listen(4000);

Menu Service v1: Code

import fetch from "node-fetch";
import Fastify from "fastify";

async function makeRequest(url) {
	const response = await fetch(url);

	const responseData = await response.json();

	return responseData;
}

const app = Fastify();

app.get("/menu", async function (request, reply) {
	const stockServiceEndpoint = "http://stock-service.icecreamcorp.net:4000/stock";

	const stockServiceResponse = await makeRequest(stockServiceEndpoint);

	reply.send({ stockServiceResponse });
});

await app.listen(3000);

Load testing and profiling the Menu Service

Menu Service v1: Behaviour

Running 60s test @ http://menu-service.icecreamcorp.net:3000/menu
100 connections

┌─────────┬────────┬─────────┬─────────┬─────────┬────────────┬────────────┬──────────┐
│ Stat    │ 2.5%   │ 50%     │ 97.5%   │ 99%     │ Avg *      │ Stdev      │ Max      │
├─────────┼────────┼─────────┼─────────┼─────────┼────────────┼────────────┼──────────┤
│ Latency │ 244 ms │ 4862 ms │ 9718 ms │ 9900 ms │ 4898.42 ms │ 2941.22 ms │ 10000 ms │
└─────────┴────────┴─────────┴─────────┴─────────┴────────────┴────────────┴──────────┘
┌───────────┬─────────┬─────────┬─────────┬─────────┬─────────┬─────────┬─────────┐
│ Stat      │ 1%      │ 2.5%    │ 50%     │ 97.5%   │ Avg *   │ Stdev   │ Min     │
├───────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
│ Req/Sec   │ 6       │ 8       │ 19      │ 27      │ 19.15   │ 4.63    │ 6       │
└───────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────┘

Req/Bytes counts sampled once per second.

1k requests in 60.03s, 539 kB read
3 errors (3 timeouts)

Menu Service v1: Behaviour

Menu Service v2: Behaviour

Running 60s test @ http://menu-service.icecreamcorp.net:3000/menu
100 connections

┌─────────┬────────┬─────────┬─────────┬─────────┬───────────┬───────────┬─────────┐
│ Stat    │ 2.5%   │ 50%     │ 97.5%   │ 99%     │ Avg *     │ Stdev     │ Max     │
├─────────┼────────┼─────────┼─────────┼─────────┼───────────┼───────────┼─────────┤
│ Latency │ 253 ms │ 1004 ms │ 1024 ms │ 1146 ms │ 957.63 ms │ 176.57 ms │ 1217 ms │
└─────────┴────────┴─────────┴─────────┴─────────┴───────────┴───────────┴─────────┘
┌───────────┬─────────┬───────┬───────┬─────────┬─────────┬────────┬─────────┐
│ Stat      │ 1%      │ 2.5%  │ 50%   │ 97.5%   │ Avg *   │ Stdev  │ Min     │
├───────────┼─────────┼───────┼───────┼─────────┼─────────┼────────┼─────────┤
│ Req/Sec   │ 13      │ 100   │ 105   │ 112     │ 103.47  │ 12.1   │ 13      │
└───────────┴─────────┴───────┴───────┴─────────┴─────────┴────────┴─────────┘

Req/Bytes counts sampled once per second.

612 2xx responses, 5596 non 2xx responses
6k requests in 60.03s, 1.97 MB read

Menu Service v2: Behaviour

The Abort API

A JavaScript API which consists of two classes:

AbortController and AbortSignal

Support for the Abort API

The Abort API originated in the Web Platform

Microsoft Edge 16 was the first browser to implement the Abort API in October 2017.

Now all major browsers support it.

Stable support in Node.js since v15.4.0, released in December 2020.

Cancelling an HTTP request with an AbortSignal

import fetch from "node-fetch";

const cancelRequest = new AbortController();

fetch("https://jsonplaceholder.typicode.com/posts", {
	signal: cancelRequest.signal
})
	.then(response => response.json())
	.then(responseData => console.log(responseData))
	.catch(error => console.error(error));

cancelRequest.abort();

$ node node-fetch-with-abortsignal.js

file:///dev/node_modules/node-fetch/src/index.js:56
			const error = new AbortError('The operation was aborted.');
			              ^

AbortError: The operation was aborted.
    at abort (file:///dev/node_modules/node-fetch/src/index.js:56:18)
    at EventTarget.abortAndFinalize (file:///dev/node_modules/node-fetch/src/index.js:75:4)
    at EventTarget.[nodejs.internal.kHybridDispatch] (node:internal/event_target:562:20)
    at EventTarget.dispatchEvent (node:internal/event_target:504:26)
    at abortSignal (node:internal/abort_controller:97:10)
    at AbortController.abort (node:internal/abort_controller:122:5)
    at file:///dev/abort-api/node-fetch-with-abortsignal.js:12:16
    at ModuleJob.run (node:internal/modules/esm/module_job:183:25)
    at async Loader.import (node:internal/modules/esm/loader:178:24)
    at async Object.loadESM (node:internal/process/esm_loader:68:5) {
  type: 'aborted'
}

Menu Service v3: Behaviour

Running 60s test @ http://menu-service.icecreamcorp.net:3000/menu
100 connections

┌─────────┬────────┬─────────┬─────────┬─────────┬──────────┬───────────┬─────────┐
│ Stat    │ 2.5%   │ 50%     │ 97.5%   │ 99%     │ Avg *    │ Stdev     │ Max     │
├─────────┼────────┼─────────┼─────────┼─────────┼──────────┼───────────┼─────────┤
│ Latency │ 282 ms │ 1006 ms │ 1116 ms │ 1167 ms │ 967.9 ms │ 172.98 ms │ 1251 ms │
└─────────┴────────┴─────────┴─────────┴─────────┴──────────┴───────────┴─────────┘
┌───────────┬─────────┬─────────┬─────────┬─────────┬─────────┬─────────┬─────────┐
│ Stat      │ 1%      │ 2.5%    │ 50%     │ 97.5%   │ Avg *   │ Stdev   │ Min     │
├───────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
│ Req/Sec   │ 4       │ 78      │ 104     │ 111     │ 102.57  │ 13.55   │ 4       │
└───────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────┘

Req/Bytes counts sampled once per second.

614 2xx responses, 5540 non 2xx responses
6k requests in 60.03s, 1.94 MB read

Menu Service v3: Behaviour

Compatibility in Node.js versions

Node.js >= v14.17.0

Enable abort classes with flag e.g. node --experimental-abortcontroller server.js

OR npm install abort-controller and:

import AbortController from "abort-controller";