2nd/10_Wiki/Topic_Programming/DevOps_and_Security/Oilpan.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-oilpan	Oilpan	10_Wiki/Topics	verified	self	Blink GC cppgc Oilpan GC	none	A	0.9	applied	gc c++ blink chromium memory-management		2026-05-10	pending	language framework C++ Blink/Chromium, cppgc (V8)

Oilpan

매 한 줄

"매 C++ object 매 trace-based GC". 매 2014 Blink (Chromium renderer) 의 DOM tree memory bug 해결 위해 도입 된 매 C++ GC. 매 2021 V8 의 매 cppgc 로 generalize 되어 매 Node.js native module / Dart VM 의 사용. 매 raw pointer 의 cycle leak 매 fundamental 해결.

매 핵심

매 motivation

• 매 DOM tree 매 cyclic reference (parent ↔ child) 매 매우 흔함.
• 매 RefCounted (smart pointer) 의 cycle 매 leak.
• 매 manual delete 매 use-after-free / double-free 폭발.
• 매 Blink 매 2010-2014 매 매 brutal memory bug 매 routine.

매 Oilpan 동작

• 매 GarbageCollected<T> base class 매 inherit → 매 GC 의 manage.
• 매 Member<T> smart pointer 매 GC-tracked field 매 declare.
• 매 Trace(Visitor*) virtual method 매 reachability 의 manual report.
• 매 incremental marking + concurrent sweeping → 매 main thread pause < 1ms.

매 응용

1. Blink DOM (Element, Node, Document) 매 모든 lifecycle.
2. V8 cppgc 매 사용 한 매 Node.js native addon.
3. Dart VM heap.
4. Skia paint object graph (experimental).

💻 패턴

1. Garbage-collected class

#include "v8/cppgc/garbage-collected.h"
#include "v8/cppgc/member.h"

class Node : public cppgc::GarbageCollected<Node> {
 public:
  void Trace(cppgc::Visitor* visitor) const {
    visitor->Trace(parent_);
    visitor->Trace(children_);
  }

 private:
  cppgc::Member<Node> parent_;
  cppgc::HeapVector<cppgc::Member<Node>> children_;
};

2. Allocation

auto* node = cppgc::MakeGarbageCollected<Node>(heap.GetAllocationHandle());
// 매 delete 의 X — GC 가 reclaim

3. Persistent (off-heap reference)

class NonGcOwner {
  cppgc::Persistent<Node> root_;  // 매 strong root
  cppgc::WeakPersistent<Node> observer_;  // 매 weak (clear 시 nullptr)
};

4. Pre-finalizer (cleanup hook)

class Resource : public cppgc::GarbageCollected<Resource> {
  USING_PRE_FINALIZER(Resource, Dispose);
  void Dispose() {
    // 매 GC 직전 호출 — 매 file handle close 등
    if (fd_ >= 0) close(fd_);
  }
  void Trace(cppgc::Visitor*) const {}
 private:
  int fd_ = -1;
};

5. Cross-thread safety

// 매 GC heap 매 single thread (renderer main).
// 매 worker → main thread post 매 cppgc::CrossThreadPersistent.
cppgc::CrossThreadPersistent<Node> handle(node);
PostTaskToMain([handle]() {
  handle->DoSomething();
});

6. Heap stats (debugging)

auto stats = heap.CollectStatistics(cppgc::HeapStatistics::DetailLevel::kDetailed);
LOG(INFO) << "Resident: " << stats.resident_size_bytes
          << " Used: " << stats.used_size_bytes;

7. Force GC (test only)

heap.ForceGarbageCollectionSlow(
    "test", "explicit",
    cppgc::Heap::StackState::kNoHeapPointers);

매 결정 기준

상황	Approach
Acyclic ownership	unique_ptr / shared_ptr (no GC needed)
Cyclic graph (DOM-like)	Oilpan / cppgc
Latency-critical realtime	Avoid — GC pause unpredictable
Cross-language boundary (V8)	cppgc 매 V8 와 매 unified heap
Embedded / no V8	Standalone cppgc library

기본값: 매 cycle 가능 한 graph 에서만 Oilpan. 매 simple ownership 매 RAII.

🔗 Graph

• 부모: Garbage Collection · Tracing GC
• 변형: V8 GC · Mark-Sweep-Compact
• Adjacent: Tri-color Marking · Reference Counting

🤖 LLM 활용

언제: 매 C++ project 에서 매 cyclic object graph 매 unavoidable. 매 V8 embedder 매 native object 와 JS object 의 unified GC. 언제 X: 매 simple resource ownership (RAII 매 충분). 매 hard real-time. 매 embedded (memory budget tight).

❌ 안티패턴

• Raw pointer 매 GC heap object 매 hold: 매 GC 가 collect → use-after-free. 매 항상 Member/Persistent.
• Trace 매 incomplete: 매 missed field 매 premature collection. 매 Clang plugin 매 lint check 활용.
• Pre-finalizer 매 heavy work: 매 GC 의 pause 증가. 매 light cleanup 만.
• Cross-thread 매 raw Member: 매 data race + 매 GC 의 oblivious. 매 CrossThreadPersistent 사용.
• Stack 의 conservative scan 의 abuse: 매 false retention. 매 kNoHeapPointers state 매 가능 한 사용.

🧪 검증 / 중복

• Verified (V8 cppgc docs, Blink rendering core 2026-05, Dart VM source).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — Oilpan/cppgc unified heap + Member/Persistent pattern