nodejs: worker threads are not working

[andrewhughes101]

Describe the bug When using worker threads in the nodejs stack, the following error is thrown when using appsody run:

Error: Module did not self-register

The error is not produced using a appsody build and then a docker run.

To Reproduce Steps to reproduce the behavior:

1. appsody init nodejs
2. enter the following code into your app.js

const { Worker, isMainThread, parentPort } = require('worker_threads');
if (isMainThread) {
  const worker = new Worker(__filename);
  worker.on('message', (msg) => { console.log(msg); });
} else {
  parentPort.postMessage('Hello world!');
}

3. appsody run

Expected behavior The worker thread should send a message to the main thread which should then output Hello World!. This expected behaviour can be reproduced by running node app.js in node 12 or later

Environment Details (please complete the following information):

• OS: macOS Catalina 10.15.1
• Version: appsody 0.5.2, docker 19.03.5
• Stack you are using (including the version): nodejs 0.3

Screenshots If applicable, add screenshots to help explain your problem.

[sam-github]

@andrewhughes101 This is because appmetrics-dash does not support being required into a worker_thread.

Using your app, reproduce without appsody by doing in your initialized app:

npm install appmetrics-dash
npm start --node-options --require=appmetrics-dash/attach

Fix is to do either, or all of:

1. appmetrics-dash.attach() returns immediately if ! require('worker_threads').isMainThread.
2. nodejs/node stops applying the --require=... to worker_threads
3. appsody/stacks stops auto-injecting the dashboard.