2nd/10_Wiki/Topic_Programming/Programming & Language/Scheduler API.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-scheduler-api	Scheduler API	10_Wiki/Topics	verified	self	scheduler.postTask Prioritized Task Scheduling	none	A	0.9	applied	web performance scheduling browser-api		2026-05-10	pending	language framework JavaScript Web Platform

Scheduler API

매 한 줄

"매 priority-aware task scheduling for the main thread". Scheduler API (scheduler.postTask, scheduler.yield) 는 long task breakup + priority hint (user-blocking / user-visible / background) 로 INP/responsiveness 최적화. 2026 Chromium + Firefox stable.

매 핵심

매 Priorities

• user-blocking: 매 immediate UI response (input handler post-work).
• user-visible: 매 default — visible 하지만 non-blocking.
• background: 매 lazy work (analytics, prefetch).

매 vs setTimeout(0) / requestIdleCallback

• 매 setTimeout(0): no priority, no abort.
• 매 rIC: idle only, deadline-based.
• 매 postTask: explicit priority + AbortSignal + delay.

매 응용

1. 매 long list rendering 분할.
2. 매 input handler 후 heavy work 양보.
3. 매 background data prefetch.

💻 패턴

postTask 기본

scheduler.postTask(() => doWork(), { priority: 'background' });

scheduler.yield (long task breakup)

async function processItems(items) {
  for (const item of items) {
    process(item);
    if (navigator.scheduling?.isInputPending?.() || items.indexOf(item) % 50 === 0) {
      await scheduler.yield();
    }
  }
}

TaskController로 abort

const controller = new TaskController({ priority: 'user-visible' });
scheduler.postTask(longJob, { signal: controller.signal });
// 매 cancel
controller.abort();
// 매 priority 동적 변경
controller.setPriority('background');

Delay

scheduler.postTask(refresh, { priority: 'background', delay: 5000 });

Polyfill fallback

const yield_ = () =>
  globalThis.scheduler?.yield?.() ??
  new Promise(r => setTimeout(r, 0));

React + Scheduler API

// React 19+ 의 useTransition + scheduler integration
startTransition(() => {
  scheduler.postTask(() => setState(heavy), { priority: 'background' });
});

매 결정 기준

상황	Approach
Heavy work after input	scheduler.yield() mid-loop
Lazy prefetch	postTask({priority:'background'})
Cancel-able task	TaskController
Idle-only callback	requestIdleCallback
매 simple deferral	queueMicrotask

기본값: 매 long loops 의 scheduler.yield() + 매 background work postTask({priority:'background'}).

🔗 Graph

• 부모: Core Web Vitals Optimization (INP, LCP, CLS)
• 응용: INP_Optimization
• Adjacent: AbortController · React_useTransition

🤖 LLM 활용

언제: 매 INP regression 발견 + 매 long task (>50ms) breakup 필요 시. 매 prioritized background work. 언제 X: 매 worker offload 가 더 적합한 CPU-heavy work, 또는 매 framework scheduler (React) 가 이미 처리.

❌ 안티패턴

• postTask 안 yield: 매 single long callback 은 여전히 long task. 매 internally yield 필요.
• user-blocking 남용: 매 priority inversion 의. 매 진짜 input-critical 만.
• Polyfill 없는 production deploy: 매 Safari 일부 버전 미지원.

🧪 검증 / 중복

• Verified (W3C Prioritized Task Scheduling, web.dev/optimize-inp).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — postTask + yield patterns