├── .gitignore
├── package.json
├── readme.md
└── server.js


/.gitignore:
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1 | /node_modules
2 | npm-debug.log
3 | 


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/package.json:
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 1 | {
 2 |   "name": "example-concurrency",
 3 |   "version": "1.0.1",
 4 |   "description": "A Heroku Example for WEB_CONCURRENCY",
 5 |   "repository": "https://github.com/heroku-examples/node-concurrency.git",
 6 |   "readme": "https://github.com/heroku-examples/node-concurrency/blob/main/readme.md",
 7 |   "main": "server.js",
 8 |   "scripts": {
 9 |     "start": "node server.js"
10 |   },
11 |   "author": "Hunter Loftis <hunter@hunterloftis.com>",
12 |   "license": "ISC",
13 |   "engines": {
14 |     "node": "10.15.0",
15 |     "npm": "6.4.1"
16 |   },
17 |   "dependencies": {
18 |     "express": "^4.16.4",
19 |     "throng": "^4.0.0"
20 |   }
21 | }


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/readme.md:
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 1 | # Load Testing
 2 | 
 3 | ```
 4 | $ heroku addons:create blazemeter
 5 | $ heroku addons:open blazemeter
 6 | ```
 7 | 
 8 | Then set up a URL test to benchmark different classes of apps:
 9 | 
10 | - `/cpu` for CPU-bound apps
11 | - `/io` for IO-bound apps
12 | - `/memory` for memory-bound apps
13 | - `/` for a no-op route
14 | 
15 | This yields a hello-world type of baseline. The CPU-bound test does a little bit of computation, and then responds. The IO-bound test simulates waiting for a resource for 300ms, then responds. The memory-bound test generates a new 1 MB string for each response. The no-op route does essentially no work and generates the best performance you can expect with the given service and network configuration.
16 | 
17 | 


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/server.js:
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 1 | const throng = require('throng')
 2 | 
 3 | const WORKERS = process.env.WEB_CONCURRENCY || 1
 4 | const PORT = process.env.PORT || 3000
 5 | 
 6 | throng({
 7 |   workers: WORKERS,
 8 |   lifetime: Infinity
 9 | }, start)
10 | 
11 | function start() {
12 |   const crypto = require('crypto')
13 |   const express = require('express')
14 |   const app = express()
15 | 
16 |   app
17 |     .get('/cpu', cpuBound)
18 |     .get('/memory', memoryBound)
19 |     .get('/io', ioBound)
20 |     .get('/', hello)
21 |     .listen(PORT, onListen)
22 | 
23 |   function hello(req, res, next) {
24 |     res.send('Hello, world')
25 |   }
26 | 
27 |   function cpuBound(req, res, next) {
28 |     const key = Math.random() < 0.5 ? 'ninjaturtles' : 'powerrangers'
29 |     const hmac = crypto.createHmac('sha512WithRSAEncryption', key)
30 |     const date = Date.now() + ''
31 |     hmac.setEncoding('base64')
32 |     hmac.end(date, () => res.send('A hashed date for you! ' + hmac.read()))
33 |   }
34 | 
35 |   function memoryBound(req, res, next) {
36 |     const large = Buffer.alloc(10 * 1024 * 1024, 'X')
37 |     setTimeout(() => {
38 |       const len = large.length  // close over the Buffer for 1s to try to foil V8's optimizations and bloat memory
39 |       console.log(len)
40 |     }, 1000).unref()
41 |     res.send('Allocated 10 MB buffer')
42 |   }
43 | 
44 |   function ioBound(req, res, next) {
45 |     setTimeout(function SimulateDb() {
46 |       res.send('Got response from fake db!')
47 |     }, 300).unref()
48 |   }
49 | 
50 |   function onListen() {
51 |     console.log('Listening on', PORT)
52 |   }
53 | }
54 | 


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