Clustering attempt will show warning on non-Linux platforms.

[schamberg97]

uWebSockets.js clustering doesn't really work on any platform other than Linux, since it depends on Linux kernel features. This can be proven with this code:

const cero = require('../src/server')
const { Worker, isMainThread, threadId } = require('worker_threads')
const numCPUs = require('os').cpus().length

if (isMainThread) {
  console.log(`Master ${process.pid} is running`)
  for (let i = 0; i < numCPUs; i++) {
    new Worker(__filename)
  }
} else {
  const server = cero({})
  server.on('request', (req, res) => {
    res.end(threadId.toString()) // willl always send '1' on non-Linux platforms.
  })

  server.listen(3000, () => {
    console.log(`Server(${threadId}) listening on http://0.0.0.0:3000`)
  })
}

As such, we need to show warning to the users, so they are aware of the issue and why there is no performance gain.

[schamberg97]

Additionally, it would make sense to point out in the docs that the best approach is to create uWebSockets.js servers on different ports that are then load balanced by something else