Scheduler

Why setTimeout Can Only Be Set to 4ms Minimum

However, if the specified timeout is too short, the browser may not have enough time to process other tasks in the queue before executing your function. This can lead to a phenomenon called “starvation” where some tasks are never executed because the browser is too busy executing the short timeouts.

https://medium.com/geekculture/why-settimeout-can-only-be-set-to-4ms-minimum-7ad9e2c2822e

비교

setTimeout(fn, 0)

평균 딜레이: 0ms

MessageChannel

평균 딜레이: 0ms

queueMicrotask

평균 딜레이: 0ms

?????

https://developer.mozilla.org/en-US/docs/Web/API/Window/queueMicrotask

큐 타입	대표 예시	처리 시점	우선순위
Microtask Queue	`Promise.then`, `queueMicrotask`	현재 실행 중인 task 이후, 렌더링 전에	⭐ 가장 빠름
Macrotask Queue (Task Queue)	`setTimeout`, `setInterval`, `setImmediate`, `MessageChannel`	모든 microtask 처리 후, 렌더링 이후	느림
Render Queue (브라우저 내부)	`requestAnimationFrame`	렌더 직전	직접 제어 불가

Date vs performance.now

Unlike Date.now, the timestamps returned by performance.now() are not limited to one-millisecond resolution. Instead, they represent times as floating-point numbers with up to microsecond precision.

Date.now()

performance.now()

Meltdown 또는 Spectre를 악용하려면 공격자가 메모리에서 특정 값을 읽는 데 걸리는 시간을 측정해야 합니다. 이를 위해서는 안정적이고 정확한 타이머가 필요합니다.

웹 플랫폼에서 제공하는 API 중 하나는 5마이크로초까지 정확한 performance.now()입니다. 완화 조치로 모든 주요 브라우저는 공격을 더 어렵게 만들기 위해 performance.now()의 해상도를 낮췄습니다.

https://developer.chrome.com/blog/meltdown-spectre?utm_source=chatgpt.com&hl=ko

Scheduler API

export {
  ImmediatePriority as unstable_ImmediatePriority,
  UserBlockingPriority as unstable_UserBlockingPriority,
  NormalPriority as unstable_NormalPriority,
  IdlePriority as unstable_IdlePriority,
  LowPriority as unstable_LowPriority,
  unstable_runWithPriority,
  unstable_next,
  unstable_scheduleCallback,
  unstable_cancelCallback,
  unstable_wrapCallback,
  unstable_getCurrentPriorityLevel,
  shouldYieldToHost as unstable_shouldYield,
  unstable_requestPaint,
  unstable_continueExecution,
  unstable_pauseExecution,
  unstable_getFirstCallbackNode,
  getCurrentTime as unstable_now,
  forceFrameRate as unstable_forceFrameRate,
};

export const unstable_Profiling = enableProfiling
  ? {
      startLoggingProfilingEvents,
      stopLoggingProfilingEvents,
    }
  : null;

Quiz

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