heroku-examples/node-concurrency

An example of Heroku's WEB_CONCURRENCY with Node.js

Load Testing

$ heroku addons:create blazemeter
$ heroku addons:open blazemeter

Then set up a URL test to benchmark different classes of apps:

• /cpu for CPU-bound apps
• /io for IO-bound apps
• /memory for memory-bound apps
• / for a no-op route

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.

node-concurrency's Issues

Followed the sample and getting Error about PORT in use

Continually getting this port conflict error:

Error: listen EADDRINUSE: address already in use :::55475

Using this basic code to start:

 const throng = require('throng')
 const WORKERS = process.env.WEB_CONCURRENCY || 5

...

function startProdApp() {
  var app = require('../app');
  let port = process.env.PORT;
  function onListen() {
    console.log('Listening on', port)
  }
  app.listen(port, onListen)
}

if(process.env.NODE_ENV === 'development'){
  startApp()
} else {
  throng({
       master: startProdApp(),
       worker: startProdApp(),
       count: WORKERS,
       lifetime: Infinity
   })
}

Heroku won't fork it appears - throng requires declaring the master and worker functions now https://github.com/hunterloftis/throng/blob/master/examples/complex.js

  if (typeof worker !== 'function') {
    throw new Error('Start function required');
  }

An example of Procfile to show

Procfile should exist in this repo.