multiprocess node test (requires linestream)

multiprocess.js

var spawn    = require('child_process').spawn;
var exec     = require('child_process').exec;
var LineStream = require('linestream');

var parallel = Number(process.argv[2]) || 40;
var N = 1000;
var script = 'number.js';
var total = 0;
var endcount = 0;

exec('which node', function(err, stdout, stderr) {
  var exepath = (stdout.charAt(stdout.length -1) == '\n') ? stdout.slice(0, -1) : stdout;
  for (var i=0; i < parallel; i++) {
    var node = spawn(exepath, [script, N]);
    var lstream = new LineStream(node.stdout, {trim: true});
    lstream.on('data', function(data) {
      total += Number(data);
    });

    lstream.on('error', function(data) {
      console.log(data);
    });

    lstream.on('end', function() {
      endcount++;
      if (endcount == parallel) {
        doEnd();
      }
    });
  }

});

function doEnd() {
  console.log('total: ' + total);
  var expected = 0;
  for (var i=0; i < N; i++) {
    expected += i;
  }
  console.log('expected: ' + expected * parallel);
}

number.js

var limit = Number(process.argv[2]) || 100000;
for (var i=0; i < limit; i++) {
  console.log(i);
}