Created
May 6, 2017 01:44
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Node.js hot-reloading using Cluster
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const express = require('express') | |
const app = express() | |
app.get('/', (req, res) => { | |
res.status(200) | |
.contentType('application/json') | |
.json({ hello: 'world' }) | |
}) | |
module.exports = app |
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{ | |
"name": "hotreload-example", | |
"version": "1.0.0", | |
"author": "Luis Farzati <lfarzati@gmail.com>", | |
"scripts": { | |
"start": "node .", | |
"dev": "NODE_ENV=development npm start" | |
}, | |
"dependencies": { | |
"express": "^4.15.2" | |
}, | |
"devDependencies": { | |
"chokidar": "^1.6.1" | |
} | |
} |
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const start = () => { | |
require('./app').listen(3000, () => console.log(`Server ready at port 3000`)) | |
} | |
if (process.env.NODE_ENV !== 'development') { | |
return start() | |
} | |
const fork = (cluster) => { | |
let worker = cluster.fork() | |
worker.on('disconnect', () => console.log(`[WORKER-${worker.id}] terminated`)) | |
console.log(`[MASTER] forked worker ${worker.id}`) | |
return worker | |
} | |
const setupMaster = (cluster) => { | |
const chokidar = require('chokidar') | |
const watcher = chokidar.watch('./app') | |
let worker = fork(cluster) | |
watcher.on('ready', () => { | |
watcher.on('all', (event, filename) => { | |
worker.send({ type: 'hotreload', args: { filename, id: worker.id } }) | |
setTimeout(((worker) => () => worker.kill())(worker), 1000) | |
process.nextTick(() => worker = fork(cluster)) | |
}) | |
}) | |
} | |
const cluster = require('cluster') | |
if (cluster.isMaster) { | |
setupMaster(cluster) | |
} | |
else if (cluster.isWorker) { | |
start() | |
process.on('message', ({type, args}) => { | |
if (type === 'hotreload') { | |
console.log(`[WORKER-${args.id}] Hot-reloading ${args.filename}`) | |
delete require.cache[require.resolve(`./${args.filename}`)] | |
process.disconnect() | |
} | |
}) | |
} |
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