perf_hooks.monitorEventLoopDelay([options])

• options <Object>
  • resolution <number> 以毫秒为单位的采样率。 必须大于零。 默认值: 10。
• 返回: <Histogram>

此属性是 Node.js 的扩展。 它在 Web 浏览器中不可用。

延迟将以纳秒为单位报告。

使用计时器来检测近似的事件循环延迟是有效的，因为计时器的执行与 libuv 事件循环的生命周期特别相关。 也就是说，循环中的延迟会导致计时器执行的延迟，而这些延迟正是此 API 旨在检测的。

const { monitorEventLoopDelay } = require('perf_hooks');
const h = monitorEventLoopDelay({ resolution: 20 });
h.enable();
// 做点什么。
h.disable();
console.log(h.min);
console.log(h.max);
console.log(h.mean);
console.log(h.stddev);
console.log(h.percentiles);
console.log(h.percentile(50));
console.log(h.percentile(99));

• options <Object>
  • resolution <number> The sampling rate in milliseconds. Must be greater than zero. Default: 10.
• Returns: <Histogram>

This property is an extension by Node.js. It is not available in Web browsers.

Creates a Histogram object that samples and reports the event loop delay over time. The delays will be reported in nanoseconds.

Using a timer to detect approximate event loop delay works because the execution of timers is tied specifically to the lifecycle of the libuv event loop. That is, a delay in the loop will cause a delay in the execution of the timer, and those delays are specifically what this API is intended to detect.

const { monitorEventLoopDelay } = require('perf_hooks');
const h = monitorEventLoopDelay({ resolution: 20 });
h.enable();
// Do something.
h.disable();
console.log(h.min);
console.log(h.max);
console.log(h.mean);
console.log(h.stddev);
console.log(h.percentiles);
console.log(h.percentile(50));
console.log(h.percentile(99));