Monitor CPU usage for a specific process

gistfile1.js

var usage = require('usage');
var log4js = require('log4js');

log4js.clearAppenders();
log4js.addAppender(log4js.appenders.console(log4js.layouts.basicLayout));

var pid = process.argv[2];
var logger = log4js.getLogger('CPU(' + pid + ')');

var interval = setInterval(function () {
    usage.lookup(pid, { keepHistory: true }, function (error, result) {
        if (error) {
            if (error.errno == 34 && error.code == 'ENOENT') {
                logger.info('Process ' + pid + ' terminated');
                clearInterval(interval);
            }
            else {
                logger.error('ERROR');
                logger.error(JSON.stringify(error, null, 2));
            }
        }
        else {
            logger.info(result.cpu);
        }
    });
}, 500);