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

Question

Is there a way to find out the cpu usage in % for a node.js process via code. So that when the node.js application is running on the server and detects the CPU exceeds certain %

Answer 1

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);