koriweb
d8a80f6272
이름만 다른(표기 변형) [[위키링크]]를 대상 문서의 canonical 제목으로 치환해 끊겼던 1,200개 링크를 연결. 제목/파일명 정규화 일치만 적용하고 별칭 매칭은 과병합 위험으로 제외(애매성 가드). 원본은 _link_reconcile_backup/ 에 백업. 도구: Datacollect/scripts/link_reconcile_apply.mjs Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
158 lines
4.8 KiB
Markdown
158 lines
4.8 KiB
Markdown
---
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id: wiki-2026-0508-snapshots
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title: Snapshots
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category: 10_Wiki/Topics
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status: verified
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canonical_id: self
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aliases: [State Snapshot, V8 Snapshot, GC Snapshot, Heap Snapshot]
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duplicate_of: none
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source_trust_level: A
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confidence_score: 0.9
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verification_status: applied
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tags: [runtime, performance, debugging, memory, state]
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raw_sources: []
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last_reinforced: 2026-05-10
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github_commit: pending
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tech_stack:
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language: javascript
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framework: v8
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---
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# Snapshots
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## 매 한 줄
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> **"매 point-in-time 의 state freeze — 매 startup 의 accelerate, 매 leak 의 hunt, 매 recovery 의 enable."**. 매 V8 startup snapshot, heap snapshot, filesystem snapshot (ZFS/Btrfs), DB snapshot, state snapshot (Redux time-travel) — 매 same primitive 의 different domain. 매 modern runtime 의 cold-start optimization 의 default tool.
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## 매 핵심
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### 매 종류
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- **V8 startup snapshot**: serialize heap → fast Node.js cold start.
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- **Heap snapshot** (`.heapsnapshot`): debug memory leak, retainer graph.
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- **GC snapshot**: generational scan checkpoint.
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- **Filesystem snapshot**: ZFS/Btrfs/LVM copy-on-write point-in-time.
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- **DB snapshot**: PITR base, transactional checkpoint.
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- **State snapshot**: Redux DevTools time-travel, game save.
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### 매 properties
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- Copy-on-write (efficient diff storage).
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- Atomic (consistent point-in-time).
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- Restorable (full state reconstruction).
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- Immutable (snapshot itself never mutated).
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### 매 응용
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1. Node.js bootup `--snapshot-blob` (200ms → 30ms startup).
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2. Chrome DevTools heap profiler — leak hunt.
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3. ZFS rollback before risky deploy.
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4. Postgres PITR base + WAL replay.
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5. Redux DevTools — time-travel debug.
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6. AWS EBS snapshot — disaster recovery.
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7. Container checkpoint/restore (CRIU).
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## 💻 패턴
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### Node.js startup snapshot
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```bash
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node --snapshot-blob snapshot.blob --build-snapshot snapshot-init.js
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node --snapshot-blob snapshot.blob app.js
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# Cold start: 200ms → ~30ms
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```
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### Chrome heap snapshot programmatic
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```javascript
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const v8 = require('v8');
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const fs = require('fs');
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const stream = v8.getHeapSnapshot();
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stream.pipe(fs.createWriteStream('heap.heapsnapshot'));
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// Open in Chrome DevTools → Memory tab
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```
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### ZFS snapshot + rollback
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```bash
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zfs snapshot tank/data@before-deploy
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# ... risky operation ...
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zfs rollback tank/data@before-deploy # if failure
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zfs destroy tank/data@before-deploy # if success
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```
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### Postgres base backup + PITR
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```bash
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pg_basebackup -D /backup/base -F tar -X stream -P
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# Recover to point-in-time
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restore_command = 'cp /archive/%f %p'
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recovery_target_time = '2026-05-10 14:30:00'
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```
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### Redux state snapshot
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```typescript
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import { createStore } from 'redux';
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const store = createStore(reducer);
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const snapshot = store.getState(); // freeze
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// ... actions ...
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store.replaceReducer((state = snapshot) => state); // restore
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```
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### CRIU container checkpoint
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```bash
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criu dump --tree $PID --images-dir /checkpoints/svc-1 --leave-running
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# Later, possibly on different host:
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criu restore --images-dir /checkpoints/svc-1
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```
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### EBS snapshot via AWS SDK
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```typescript
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import { EC2Client, CreateSnapshotCommand } from '@aws-sdk/client-ec2';
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await client.send(new CreateSnapshotCommand({
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VolumeId: 'vol-0abc',
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Description: 'pre-migration-2026-05-10',
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TagSpecifications: [{ ResourceType: 'snapshot', Tags: [{ Key: 'env', Value: 'prod' }] }],
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}));
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```
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### Heap diff analysis
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```javascript
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// Take 2 snapshots, diff in DevTools to find leak
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v8.writeHeapSnapshot('/tmp/before.heapsnapshot');
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runSuspectCode();
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v8.writeHeapSnapshot('/tmp/after.heapsnapshot');
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// Load both → "Comparison" view → growing retainer chains
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```
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## 매 결정 기준
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| 상황 | Approach |
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|---|---|
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| Node.js cold start slow | startup snapshot |
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| Memory leak hunt | heap snapshot diff |
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| Pre-deploy rollback safety | ZFS/EBS snapshot |
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| DB recovery to time T | PITR base + WAL |
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| Container live migration | CRIU checkpoint |
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| Frontend bug repro | Redux time-travel |
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**기본값**: heap snapshot for leaks, ZFS/EBS for storage, PITR for DB, CRIU for container.
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## 🔗 Graph
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- 부모: [[State Management]]
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- 변형: [[Heap Snapshot]] · [[V8-Snapshot]]
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- 응용: [[Disaster-Recovery]]
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- Adjacent: [[Event Sourcing]]
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## 🤖 LLM 활용
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**언제**: cold-start optim, leak diag, DR planning, time-travel debug strategy.
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**언제 X**: write-heavy hot path — snapshot overhead 의 measure 필요.
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## ❌ 안티패턴
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- **Snapshot as backup**: 매 same disk 의 snapshot 의 disk failure 의 protect X.
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- **No retention policy**: 매 snapshot accumulate → storage explode.
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- **Heap snapshot in prod under load**: 매 GC pause spike — staging 에서.
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## 🧪 검증 / 중복
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- Verified (V8 docs, Chrome DevTools docs, ZFS handbook, Postgres PITR docs).
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- 신뢰도 A.
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## 🕓 Changelog
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| 날짜 | 변경 |
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|---|---|
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| 2026-05-08 | Phase 1 |
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| 2026-05-10 | Manual cleanup — snapshot taxonomy, V8/heap/ZFS/PITR/CRIU patterns |
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