How can I execute a node.js module as a child process of a node.js program?

Question

Here\'s my problem. I implemented a small script that does some heavy calculation, as a node.js module. So, if I type \"node myModule.js\", it calculates for a second, then

Answer 1

I think what you're after is the child_process.fork() API.

For example, if you have the following two files:

In main.js:

var cp = require('child_process');
var child = cp.fork('./worker');

child.on('message', function(m) {
  // Receive results from child process
  console.log('received: ' + m);
});

// Send child process some work
child.send('Please up-case this string');

In worker.js:

process.on('message', function(m) {
  // Do work  (in this case just up-case the string
  m = m.toUpperCase();

  // Pass results back to parent process
  process.send(m.toUpperCase(m));
});

Then to run main (and spawn a child worker process for the worker.js code ...)

$ node --version
v0.8.3

$ node main.js 
received: PLEASE UP-CASE THIS STRING

Answer 2

It doesn't matter what you will use as a child (Node, Python, whatever), Node doesn't care. Just make sure, that your calculcation script exits after everything is done and result is written to stdout.

Reason why it's not working is that you're using spawn instead of exec.