Ensure maxListeners for process.stdout accounts for workers

[marcins]

↪️ Pull Request

Fixes the MaxListenersExceededWarning warnings that would occur in environments with > 10 workers.

This occurs because by default Node will pipe worker stdout to process stdout, however it doesn't increase the maxListener property of the process.stdout event emitter.

This behaviour was validated with a simple test script - added 20 workers and process.stdout.getMaxListeners() was still 10, piping to stdout resulted in a warning about 21 listeners.

The "Ora" library used by the CLI Reporter also pipes into process.stdout, and when this pipe is connected this triggers the warnings as worker_count + 1 > 10 (which is the default maxListener value).

As a fix we will set the process.stdout.setMaxListeners() to equal to the worker count + 1. This isn't perfect, especially if something else hooks into process.stdout in future, but due to the limitation of calling process.stdout.getMaxListeners() mentioned above is at least a better outcome for Parcel out of the box.

Related in the context of Parcel: sindresorhus/ora#162

🚨 Test instructions

Before the patch - run Parcel with:

❯ PARCEL_WORKERS=20 node ./node_modules/.bin/parcel build --no-cache packages/examples/ts-example/src/index.ts

console: (node:4012) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 21 unpipe listeners added to [WriteStream]. Use 
emitter.setMaxListeners() to increase limit
(Use `node --trace-warnings ...` to show where the warning was created)
[...]

After the patch the same command does not trigger any warnings.

✔️ PR Todo

• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs