text: 
  
  const path = require('path');
  const async = require('async');
  const lf = require('lockfile');
  const cp = require('child_process');
  
  const start = Date.now();
  
  async.times(8, function(num, cb){
  
    const k = cp.spawn('node',[path.resolve(__dirname + '/lf-child.js')]);
    k.stderr.pipe(process.stderr);
    k.once('exit', cb);
  
  }, function(err){
  
    if(err){
      throw err;
    }
  
  
    console.log('total time:', Date.now()- start);
    process.exit(0);
  
  
  });