Worker message event triggers when worker process sends

[PsySecCorp]

Running Node v11.12.0 on Windows 7

Filename: IsClusterStillAlpha.js

const cluster = require('cluster')

if (cluster.isMaster) {
  // Master
  const worker = cluster.fork()

  worker.on('message', function (message) {
    console.log('worker got message:', message)
  })
} else if (cluster.isWorker) {
  // Worker
  process.send('sending worker to master')
}

Command to run the script: node IsClusterStillAlpha.js

Core assumption: Worker's can be assigned .on('message', ...) within the master process as per https://github.com/nodejs/node/blame/master/doc/api/cluster.md#L240.
Expected output: Nothing
Actual output: worker got message: sending worker to master

[bnoordhuis]

The sample works as expected and it's unclear to me why you expect it to not print anything. Can you elaborate?

[PsySecCorp]

@bnoordhuis Thanks for getting back to me.

The documentation alludes to process.send notifying the master process, but that the worker.on('message', ...) listener is executed WITHIN the worker process. Is the worker listener executed within the master process?

[bnoordhuis]

Yes. I think you are confusing it with process.on('message', ...) - that executes in the worker process.

[cjihrig]

Closing as answered.