Design Complete Monitor for System Uptime and Load Average

🚀 Building a CPU & Memory Monitor in Node.js

node:os module imports the CPU info, memory info , uptime, system-level stats they all are coming from the os module.

we design a function named monitor which calculate the CPU and Memory usage.

oldCpus=os.cpus(); : This is calculating the cpus info like idle time, user time, system time etc.

we call a method setTimeout() : This will call repeatly os.cpus() method for the comparison purpose . Like idle=newCpus-oldCpus

const newCpus=os.cpus(); : This calculate the new cpus stats.

   const usage = newCpus.map((cpu, idx) => {

      return {

        core: idx,

        usage: calculateCPU(oldCpus[idx], newCpus[idx]) + "%",

      };

    });

This is calculating the usage for CPU Core where loop will execute for every core with the help of map() method and calculate the 

usage percentage = calculateCPU(oldCpus[idx], newCpus[idx])

output like:

[

  { core: 0, usage: "10.5%" },

  { core: 1, usage: "7.8%" }

]

print the table form these array

    console.clear();

    console.table(usage);

like this

┌─────────┬──────┬─────────┐

│ (index) │ core │ usage   │

├─────────┼──────┼─────────┤

│    0    │  0   │ '12.3%' │

│    1    │  1   │ '8.7%'  │

└─────────┴──────┴─────────┘

This line 

    const usedMemory = (os.totalmem() - os.freemem()) / (1024 * 1024 * 1024);

This line calculate the total memory and free memory and usages memory

import os from "node:os"; function monitor() {

  const oldCpus = os.cpus();

  setTimeout(() => {

    const newCpus = os.cpus();

    const usage = newCpus.map((cpu, idx) => {

      return {

        core: idx,

        usage: calculateCPU(oldCpus[idx], newCpus[idx]) + "%",

      };

    });

    console.clear();

    console.table(usage);

    const usedMemory = (os.totalmem() - os.freemem()) / (1024 * 1024 * 1024);

    console.log(

      `Memory Used: ${usedMemory.toFixed(2)} GB/${(

        os.totalmem() /

        (1024 * 1024 * 1024)

      ).toFixed(2)} GB`

    );

  }, 1000);

}

function calculateCPU(oldCpus, newCpus) {

  const oldTotal = Object.values(oldCpus.times).reduce((a, b) => a + b);

  const newTotal = Object.values(newCpus.times).reduce((a, b) => a + b);

  const idle = newCpus.times.idle - oldCpus.times.idle;

  const total = newTotal - oldTotal;

  const used = total - idle;

  return ((100 * used) / total).toFixed(1);

}

setInterval(monitor, 1000);