How to get CPU usage

Question

My Go program needs to know the current cpu usage percentage of all system and user processes.

How can I obtain that?

Answer 1

You can use the os.exec package to execute the ps command and get the result.

Here is a program issuing the ps aux command, parsing the result and printing the CPU usage of all processes on linux :

package main

import (
    "bytes"
    "log"
    "os/exec"
    "strconv"
    "strings"
)

type Process struct {
    pid int
    cpu float64
}

func main() {
    cmd := exec.Command("ps", "aux")
    var out bytes.Buffer
    cmd.Stdout = &out
    err := cmd.Run()
    if err != nil {
        log.Fatal(err)
    }
    processes := make([]*Process, 0)
    for {
        line, err := out.ReadString('\n')
        if err!=nil {
            break;
        }
        tokens := strings.Split(line, " ")
        ft := make([]string, 0)
        for _, t := range(tokens) {
            if t!="" && t!="\t" {
                ft = append(ft, t)
            }
        }
        log.Println(len(ft), ft)
        pid, err := strconv.Atoi(ft[1])
        if err!=nil {
            continue
        }
        cpu, err := strconv.ParseFloat(ft[2], 64)
        if err!=nil {
            log.Fatal(err)
        }
        processes = append(processes, &Process{pid, cpu})
    }
    for _, p := range(processes) {
        log.Println("Process ", p.pid, " takes ", p.cpu, " % of the CPU")
    }
}