How to find out the % CPU usage for Node.js process?

On *nix systems can get process stats by reading the /proc/[pid]/stat virtual file.

For example this will check the CPU usage every ten seconds, and print to the console if it's over 20%. It works by checking the number of cpu ticks used by the process and comparing the value to a second measurement made one second later. The difference is the number of ticks used by the process during that second. On POSIX systems, there are 10000 ticks per second (per processor), so dividing by 10000 gives us a percentage.

var fs = require('fs');

var getUsage = function(cb){
    fs.readFile("/proc/" + process.pid + "/stat", function(err, data){
        var elems = data.toString().split(' ');
        var utime = parseInt(elems[13]);
        var stime = parseInt(elems[14]);

        cb(utime + stime);
    });
}

setInterval(function(){
    getUsage(function(startTime){
        setTimeout(function(){
            getUsage(function(endTime){
                var delta = endTime - startTime;
                var percentage = 100 * (delta / 10000);

                if (percentage > 20){
                    console.log("CPU Usage Over 20%!");
                }
            });
        }, 1000);
    });
}, 10000);

Try looking at this code: https://github.com/last/healthjs

Network service for getting CPU of remote system and receiving CPU usage alerts...

Health.js serves 2 primary modes: "streaming mode" and "event mode". Streaming mode allows a client to connect and receive streaming CPU usage data. Event mode enables Health.js to notify a remote server when CPU usage hits a certain threshold. Both modes can be run simultaneously...