以百分比获取进程 CPU 使用率

Question

process.cpuUsage() 函数显示了一些奇怪的微秒值。 如何获取 cpu 使用百分比？

Answer 1

尝试使用下面的代码来获取 % 中的 cpu 使用率

var startTime  = process.hrtime()
var startUsage = process.cpuUsage()

// spin the CPU for 500 milliseconds
var now = Date.now()
while (Date.now() - now < 500)

var elapTime = process.hrtime(startTime)
var elapUsage = process.cpuUsage(startUsage)

var elapTimeMS = secNSec2ms(elapTime)
var elapUserMS = secNSec2ms(elapUsage.user)
var elapSystMS = secNSec2ms(elapUsage.system)
var cpuPercent = Math.round(100 * (elapUserMS + elapSystMS) / elapTimeMS)

console.log('elapsed time ms:  ', elapTimeMS)
console.log('elapsed user ms:  ', elapUserMS)
console.log('elapsed system ms:', elapSystMS)
console.log('cpu percent:      ', cpuPercent)

function secNSec2ms (secNSec) {
  return secNSec[0] * 1000 + secNSec[1] / 1000000
}

尝试将secNSec2ms function 调整为以下内容，以检查它是否能解决您的问题。

function secNSec2ms(secNSec) {
  if (Array.isArray(secNSec))
  return secNSec[0] * 1000 + secNSec[1] / 1000000 return secNSec / 1000;
}

Answer 2

您可以使用附加的 os 本机模块来获取有关您的 CPU 的信息：

const os = require('os');

// Take the first CPU, considering every CPUs have the same specs
// and every NodeJS process only uses one at a time.
const cpus = os.cpus();
const cpu = cpus[0];

// Accumulate every CPU times values
const total = Object.values(cpu.times).reduce(
    (acc, tv) => acc + tv, 0
);

// Normalize the one returned by process.cpuUsage() 
// (microseconds VS miliseconds)
const usage = process.cpuUsage();
const currentCPUUsage = (usage.user + usage.system) * 1000;

// Find out the percentage used for this specific CPU
const perc = currentCPUUsage / total * 100;

console.log(`CPU Usage (%): ${perc}`);

如果您想获取全局 CPU 使用率（考虑到所有 CPU），则需要累积每个 CPU 的每次，不仅是第一个，而且在大多数情况下应该不太有用。

请注意，只有“系统”时间才能使用比第一个 CPU 更多的时间，因为调用可以在与 NodeJS 核心分离的其他线程中运行。

来源：

• https://nodejs.org/api/os.html#os_os_cpus

• https://nodejs.org/api/process.html#process_process_cpuusage_previousvalue

Answer 3

在回答之前，我们需要注意几个事实：

• Node.js 不只使用一个 CPU，但每个异步 I/O 操作都可能使用额外的 CPU
• process.cpuUsage 返回的时间是 Node.js 进程使用的所有 CPU 的累积时间

所以要考虑到主机的所有 CPU 来计算 Node.js 的 CPU 使用率，我们可以使用类似的东西：

const ncpu = require("os").cpus().length;
let previousTime = new Date().getTime();
let previousUsage = process.cpuUsage();
let lastUsage;

setInterval(() => {
    const currentUsage = process.cpuUsage(previousUsage);

    previousUsage = process.cpuUsage();

    // we can't do simply times / 10000 / ncpu because we can't trust
    // setInterval is executed exactly every 1.000.000 microseconds
    const currentTime = new Date().getTime();
    // times from process.cpuUsage are in microseconds while delta time in milliseconds
    // * 10 to have the value in percentage for only one cpu
    // * ncpu to have the percentage for all cpus af the host

    // this should match top's %CPU
    const timeDelta = (currentTime - previousTime) * 10;
    // this would take care of CPUs number of the host
    // const timeDelta = (currentTime - previousTime) * 10 * ncpu;
    const { user, system } = currentUsage;

    lastUsage = { system: system / timeDelta, total: (system + user) / timeDelta, user: user / timeDelta };
    previousTime = currentTime;

    console.log(lastUsage);
}, 1000);

或者我们可以从需要的地方读取lastUsage 的值，而不是将其打印到控制台。

Answer 4

另一种选择，假设您在 linux/macos 操作系统下运行 node。是：

var exec = require("child_process").exec;

function getProcessPercent() {

  // GET current node process id.
  const pid = process.pid;
  console.log(pid);

  //linux command to get cpu percentage for the specific Process Id.
  var cmd = `ps up "${pid}" | tail -n1 | tr -s ' ' | cut -f3 -d' '`;

  setInterval(() => {
    //executes the command and returns the percentage value
    exec(cmd, function (err, percentValue) {
      if (err) {
        console.log("Command `ps` returned an error!");
      } else {
        console.log(`${percentValue* 1}%`);
      }
    });
  }, 1000);
}

getProcessPercent();

如果您的操作系统是 windows，则您的命令必须不同。由于我没有运行 Windows，我无法告诉您确切的命令，但您可以从这里开始：

tasklist

get-process

WMIC

您还可以使用process.platform 检查平台并执行 if/else 语句为特定操作系统设置正确的命令。