cpu_not_ok_fixed_sample_size.js

const fs = require('fs');


function readStat(cb) {
  fs.readFile("/proc/" + process.pid + "/stat", function(err, data) {
    if (err) {
      return cb(err);
    }


    var elems = data.toString().split(' ');
    var utime = parseInt(elems[13]);
    var stime = parseInt(elems[14]);

    console.log('utime', utime, 'stime', stime);
    return cb(null, utime + stime);
  });
}

readStat(function(err, t1) {
  setTimeout(function() {
    readStat(function(err, t2) {
      console.log('t1', t1, 't2', t2);
      console.log('cpu percentage', 100 * ((t2 - t1) / 10000));
    });
  }, 1000);


  var j = 0;
  for(var i = 0, l = 10000000000; i<l; i++) {
    j++;
  }
  console.log('j', j);
});

cpu_ok_dynamic_sample_size.js

const fs = require('fs');


function readStat(cb) {
  fs.readFile("/proc/" + process.pid + "/stat", function(err, data) {
    if (err) {
      return cb(err);
    }


    var timeOfRead = Date.now();
    var elems = data.toString().split(' ');
    var utime = parseInt(elems[13]);
    var stime = parseInt(elems[14]);

    console.log('utime', utime, 'stime', stime);
    return cb(null, utime + stime, timeOfRead);
  });
}

readStat(function(err, t1, t1TimeOfRead) {
  setTimeout(function() {
    readStat(function(err, t2, t2TimeOfRead) {
      var secondsBetweenReads = (t2TimeOfRead - t1TimeOfRead)/1000;
      console.log('t1', t1, 't2', t2, 'secondsBetweenReads', secondsBetweenReads);
      console.log('cpu percentage', 100 * ((t2 - t1) / (10000 * secondsBetweenReads)));
    });
  }, 1000);


  var j = 0;
  for(var i = 0, l = 10000000000; i<l; i++) {
    j++;
  }
  console.log('j', j);
});