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<!DOCTYPE html>
<html lang="ko">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Ch.6 운영체제 | CS Visualizer</title>
<link href="https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@300;400;500;600;700&family=Noto+Sans+KR:wght@300;400;500;700&display=swap" rel="stylesheet">
<link rel="stylesheet" href="style.css">
<style>
/* ── ch6-only styles ── */
/* PROCESS STATE DIAGRAM */
.state-diagram-wrap{position:relative;width:100%;background:var(--surface2);border-radius:8px;overflow:hidden;}
.proc-table{width:100%;border-collapse:collapse;font-family:'JetBrains Mono',monospace;font-size:0.82rem;margin-top:16px;}
.proc-table th,.proc-table td{padding:8px 14px;border-bottom:1px solid var(--border);text-align:left;}
.proc-table th{color:var(--text-dim);}
.state-badge{display:inline-block;padding:2px 10px;border-radius:100px;font-size:0.72rem;font-family:'JetBrains Mono',monospace;}
.state-cards{display:grid;grid-template-columns:repeat(5,1fr);gap:10px;margin-top:20px;}
.state-card{background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:12px 14px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;transition:all 0.3s;}
.state-card .sc-name{font-size:0.88rem;font-weight:700;margin-bottom:5px;}
.state-card .sc-desc{color:var(--text-dim);line-height:1.6;font-size:0.72rem;}
.state-card.active-new{border-color:#8888aa;box-shadow:0 0 12px rgba(136,136,170,0.25);}
.state-card.active-ready{border-color:var(--accent3);box-shadow:0 0 12px rgba(107,138,255,0.25);}
.state-card.active-running{border-color:var(--accent);box-shadow:0 0 12px rgba(0,255,170,0.25);}
.state-card.active-waiting{border-color:var(--accent4);box-shadow:0 0 12px rgba(255,170,0,0.25);}
.state-card.active-terminated{border-color:var(--danger);box-shadow:0 0 12px rgba(255,68,102,0.25);}
/* MEMORY LAYOUT */
.mem-layout{display:flex;gap:24px;align-items:flex-start;flex-wrap:wrap;}
.mem-column{flex:1;min-width:200px;position:relative;}
.mem-addr-col{display:flex;flex-direction:column;justify-content:space-between;font-family:'JetBrains Mono',monospace;font-size:0.65rem;color:var(--text-dim);padding:4px 0;min-width:70px;align-self:stretch;}
.mem-segment{font-family:'JetBrains Mono',monospace;font-size:0.8rem;padding:10px 16px;border:1px solid var(--border);text-align:center;transition:all 0.3s;position:relative;}
.seg-code{background:rgba(0,255,170,0.08);border-color:rgba(0,255,170,0.3);color:var(--accent);}
.seg-data{background:rgba(255,170,0,0.08);border-color:rgba(255,170,0,0.3);color:var(--accent4);}
.seg-bss{background:rgba(255,170,0,0.04);border-color:rgba(255,170,0,0.2);color:var(--accent4);opacity:0.7;}
.seg-heap{background:rgba(107,138,255,0.08);border-color:rgba(107,138,255,0.3);color:var(--accent3);}
.seg-free{background:transparent;border:1px dashed var(--border);color:var(--text-dim);opacity:0.4;}
.seg-stack{background:rgba(255,107,157,0.08);border-color:rgba(255,107,157,0.3);color:var(--accent2);}
.stack-frame{background:rgba(255,107,157,0.15);border:1px solid rgba(255,107,157,0.4);border-radius:4px;padding:5px 10px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--accent2);margin-bottom:3px;animation:fadeIn 0.3s;}
.heap-block{background:rgba(107,138,255,0.15);border:1px solid rgba(107,138,255,0.4);border-radius:4px;padding:5px 10px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--accent3);margin-top:3px;animation:fadeIn 0.3s;}
.ptr-indicator{font-family:'JetBrains Mono',monospace;font-size:0.72rem;padding:4px 10px;border-radius:4px;margin:4px 0;display:flex;justify-content:space-between;}
.ptr-sp{background:rgba(255,107,157,0.1);border:1px solid rgba(255,107,157,0.3);color:var(--accent2);}
.ptr-hp{background:rgba(107,138,255,0.1);border:1px solid rgba(107,138,255,0.3);color:var(--accent3);}
.mem-warn{background:rgba(255,68,102,0.1);border:1px solid var(--danger);border-radius:6px;padding:8px 14px;font-family:'JetBrains Mono',monospace;font-size:0.78rem;color:var(--danger);margin-top:10px;display:none;}
.mem-info-panel{flex:1;min-width:200px;}
/* CONTEXT SWITCH */
.ctx-timeline{height:60px;background:var(--surface2);border-radius:8px;position:relative;overflow:hidden;margin:16px 0;}
.ctx-block{position:absolute;top:6px;bottom:6px;border-radius:4px;display:flex;align-items:center;justify-content:center;font-family:'JetBrains Mono',monospace;font-size:0.75rem;font-weight:700;transition:all 0.3s;}
.ctx-block-a{background:rgba(107,138,255,0.4);border:1px solid var(--accent3);color:var(--accent3);}
.ctx-block-b{background:rgba(255,107,157,0.4);border:1px solid var(--accent2);color:var(--accent2);}
.ctx-block-overhead{background:rgba(136,136,170,0.2);border:1px dashed var(--border);color:var(--text-dim);}
.pcb-card{background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:14px;font-family:'JetBrains Mono',monospace;font-size:0.78rem;transition:all 0.3s;}
.pcb-card.pcb-active{border-color:var(--accent);box-shadow:0 0 14px rgba(0,255,170,0.15);}
.pcb-card.pcb-saving{border-color:var(--accent4);box-shadow:0 0 14px rgba(255,170,0,0.15);animation:savePulse 0.4s;}
.pcb-card.pcb-loading{border-color:var(--success);box-shadow:0 0 14px rgba(0,204,136,0.15);animation:savePulse 0.4s;}
@keyframes savePulse{0%,100%{transform:scale(1)}50%{transform:scale(1.02)}}
.pcb-row{display:flex;justify-content:space-between;padding:3px 0;border-bottom:1px solid rgba(255,255,255,0.05);}
.pcb-key{color:var(--text-dim);}
.pcb-val{color:var(--accent);}
.ctx-counter-row{display:flex;gap:20px;flex-wrap:wrap;margin-top:12px;}
.ctx-counter{background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:10px 18px;font-family:'JetBrains Mono',monospace;font-size:0.78rem;text-align:center;}
.ctx-counter-val{font-size:1.4rem;font-weight:700;color:var(--accent);}
.ctx-counter-label{font-size:0.68rem;color:var(--text-dim);margin-top:2px;}
.ctx-pcb-row{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:16px;}
.ctx-timeline-label{font-family:'JetBrains Mono',monospace;font-size:0.72rem;color:var(--text-dim);margin-bottom:6px;}
.ctx-legend{display:flex;gap:14px;flex-wrap:wrap;margin-top:8px;}
.ctx-legend-item{display:flex;align-items:center;gap:6px;font-family:'JetBrains Mono',monospace;font-size:0.72rem;color:var(--text-dim);}
.ctx-legend-dot{width:12px;height:12px;border-radius:3px;}
/* READY QUEUE (scheduling) */
.rq-wrap{margin-top:16px;margin-bottom:16px;}
.rq-title{font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);margin-bottom:8px;}
.rq-queue{display:flex;gap:6px;align-items:center;padding:10px 12px;background:var(--surface2);border:1px solid var(--border);border-radius:8px;min-height:52px;flex-wrap:wrap;}
.rq-proc{padding:6px 14px;border-radius:6px;font-family:'JetBrains Mono',monospace;font-size:0.8rem;font-weight:700;border:1px solid;animation:fadeIn 0.3s;transition:all 0.3s;}
.rq-arrow{font-family:'JetBrains Mono',monospace;font-size:1rem;color:var(--text-dim);}
.rq-cpu{display:flex;align-items:center;gap:8px;margin-top:8px;font-family:'JetBrains Mono',monospace;font-size:0.8rem;}
.rq-cpu-box{background:rgba(0,255,170,0.08);border:2px solid var(--accent);border-radius:8px;padding:8px 20px;color:var(--accent);font-weight:700;min-width:80px;text-align:center;transition:all 0.3s;}
/* DEADLOCK CONDITIONS */
.dl-conditions{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-top:16px;}
.dl-cond{background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:14px 16px;font-family:'JetBrains Mono',monospace;cursor:pointer;transition:all 0.3s;user-select:none;}
.dl-cond:hover{border-color:var(--accent3);}
.dl-cond.checked{border-color:var(--danger);background:rgba(255,68,102,0.06);}
.dl-cond .cond-num{font-size:0.65rem;color:var(--text-dim);margin-bottom:5px;letter-spacing:1px;}
.dl-cond .cond-name{font-size:0.85rem;font-weight:700;color:var(--text);margin-bottom:4px;}
.dl-cond.checked .cond-name{color:var(--danger);}
.dl-cond .cond-desc{font-size:0.72rem;color:var(--text-dim);line-height:1.6;}
.dl-cond .cond-check{float:right;font-size:1rem;transition:all 0.2s;}
.dl-cond.checked .cond-check{color:var(--danger);}
.dl-deadlock-indicator{margin-top:14px;padding:12px 18px;border-radius:8px;font-family:'JetBrains Mono',monospace;font-size:0.85rem;font-weight:700;text-align:center;transition:all 0.3s;}
.dl-deadlock-indicator.no{background:rgba(0,204,136,0.08);border:1px solid var(--success);color:var(--success);}
.dl-deadlock-indicator.yes{background:rgba(255,68,102,0.1);border:1px solid var(--danger);color:var(--danger);animation:pulse 1.5s infinite;}
/* GENERAL */
@keyframes fadeIn{from{opacity:0;transform:scale(0.9)}to{opacity:1;transform:scale(1)}}
@keyframes pulse{0%,100%{box-shadow:0 0 0 0 rgba(255,68,102,0.3)}50%{box-shadow:0 0 20px 4px rgba(255,68,102,0.2)}}
@media(max-width:640px){
.state-cards{grid-template-columns:repeat(2,1fr);}
.ctx-pcb-row{grid-template-columns:1fr;}
.dl-conditions{grid-template-columns:1fr;}
.mem-layout{flex-direction:column;}
}
</style>
</head>
<body class="page-body">
<nav class="page-nav">
<a href="index.html" class="nav-back">← 홈</a>
<div class="nav-chapter-title" style="color:var(--success)">Ch.6 — 운영체제</div>
<div class="nav-sections">
<a href="#procstate" class="nav-sec-link">프로세스 상태</a>
<a href="#memlayout" class="nav-sec-link">메모리 구조</a>
<a href="#context" class="nav-sec-link">컨텍스트 스위칭</a>
<a href="#memory" class="nav-sec-link">메모리 관리</a>
<a href="#virtualmem" class="nav-sec-link">가상메모리</a>
<a href="#scheduling" class="nav-sec-link">스케줄링</a>
<a href="#deadlock" class="nav-sec-link">데드락</a>
<a href="#thread" class="nav-sec-link">프로세스 vs 스레드</a>
<a href="#sync" class="nav-sec-link">동기화</a>
</div>
</nav>
<div class="chapter-banner cb6">
<div class="ch-num">CHAPTER 06</div>
<h2>운영체제</h2>
<p class="ch-desc">프로세스 상태, 메모리 구조, 컨텍스트 스위칭부터 가상메모리, 스케줄링, 데드락까지 — OS 핵심 개념을 인터랙티브 시각화로 완전히 이해합니다.</p>
<div class="ch-pills">
<span>프로세스 상태</span><span>메모리 레이아웃</span><span>컨텍스트 스위칭</span>
<span>메모리 관리</span><span>가상메모리</span><span>스케줄링</span><span>데드락</span>
</div>
</div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 1: 프로세스 상태 다이어그램 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="procstate">
<div class="section-header">
<div class="tag tag-ch6">PROC</div>
<h2>프로세스 상태 (Process State Diagram)</h2>
<p>프로그램을 실행하면 OS는 프로세스를 생성합니다. 프로세스는 생명 주기 동안 5가지 상태를 거칩니다. CPU가 하나뿐이라도 여러 프로세스가 동시에 실행되는 것처럼 보이는 건 이 상태 전환 덕분입니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn" onclick="psSpawnProcess()">새 프로세스 생성</button>
<button class="btn" onclick="psTransition('ready_to_run')">CPU 획득</button>
<button class="btn" onclick="psTransition('io_request')">I/O 요청</button>
<button class="btn" onclick="psTransition('io_done')">I/O 완료</button>
<button class="btn" onclick="psTransition('timeslice')">타임슬라이스 만료</button>
<button class="btn danger" onclick="psTransition('terminate')">프로세스 종료</button>
</div>
<div class="state-diagram-wrap">
<canvas id="psCanvas" height="280"></canvas>
</div>
<div class="state-cards">
<div class="state-card" id="sc-new">
<div class="sc-name" style="color:#8888aa">NEW</div>
<div class="sc-desc">프로세스가 막 생성된 상태. OS가 PCB를 할당하고 초기화합니다.</div>
</div>
<div class="state-card" id="sc-ready">
<div class="sc-name" style="color:var(--accent3)">READY</div>
<div class="sc-desc">CPU를 받을 준비가 된 상태. 레디 큐에서 스케줄러를 기다립니다.</div>
</div>
<div class="state-card" id="sc-running">
<div class="sc-name" style="color:var(--accent)">RUNNING</div>
<div class="sc-desc">실제로 CPU에서 명령어가 실행 중인 상태. 단일 코어에서는 1개만 가능.</div>
</div>
<div class="state-card" id="sc-waiting">
<div class="sc-name" style="color:var(--accent4)">WAITING</div>
<div class="sc-desc">I/O 완료, 이벤트 등을 기다리는 상태. CPU를 소비하지 않습니다.</div>
</div>
<div class="state-card" id="sc-terminated">
<div class="sc-name" style="color:var(--danger)">TERMINATED</div>
<div class="sc-desc">실행이 끝났거나 강제 종료된 상태. OS가 PCB와 자원을 회수합니다.</div>
</div>
</div>
<table class="proc-table">
<thead><tr><th>PID</th><th>이름</th><th>현재 상태</th><th>우선순위</th><th>실행 시간</th></tr></thead>
<tbody id="psTableBody"></tbody>
</table>
<div class="info-text">버튼을 눌러 프로세스의 상태를 전환해 보세요. 선택된 프로세스(파란 테두리)에 상태 전환이 적용됩니다.<br>
💡 <strong>Tip:</strong> 실제 OS에서 NEW→READY는 fork()로, RUNNING→WAITING은 read()나 sleep() 같은 블로킹 시스템 콜로 발생합니다.</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 2: 프로세스 메모리 구조 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="memlayout">
<div class="section-header">
<div class="tag tag-ch6">MEM</div>
<h2>프로세스 메모리 구조 (Memory Layout)</h2>
<p>실행 중인 프로그램은 메모리에서 정해진 영역에 나눠 저장됩니다. 코드는 코드 세그먼트, 전역변수는 데이터 세그먼트, 동적 할당은 힙(위로), 함수 호출 스택은 스택(아래로). 힙과 스택이 만나면 메모리 오류가 납니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn" onclick="mlPushStack()">함수 호출 (push)</button>
<button class="btn" onclick="mlPopStack()">함수 반환 (pop)</button>
<button class="btn" onclick="mlMalloc()">malloc() — 힙 할당</button>
<button class="btn" onclick="mlFree()">free() — 힙 해제</button>
<button class="btn danger" onclick="mlReset()">초기화</button>
</div>
<div class="mem-layout">
<!-- Memory column diagram -->
<div class="mem-column" style="max-width:260px;">
<div style="font-family:'JetBrains Mono',monospace;font-size:0.65rem;color:var(--text-dim);text-align:right;margin-bottom:2px;">0xFFFF (High)</div>
<!-- Stack area: grows downward -->
<div id="ml-stack-area">
<div class="mem-segment seg-stack" style="min-height:30px;border-bottom:none;">
<span style="font-size:0.65rem;opacity:0.6;">↓ STACK (grows down)</span>
</div>
<div id="ml-stack-frames" style="padding:0 8px 4px;background:rgba(255,107,157,0.04);border:1px solid rgba(255,107,157,0.3);border-top:none;"></div>
</div>
<!-- Free space -->
<div class="mem-segment seg-free" id="ml-free-space" style="height:80px;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:4px;">
<span style="font-size:0.7rem;">빈 공간</span>
<span style="font-size:0.6rem;" id="ml-gap-pct">—</span>
</div>
<!-- Heap area: grows upward -->
<div id="ml-heap-area">
<div id="ml-heap-blocks" style="padding:4px 8px 0;background:rgba(107,138,255,0.04);border:1px solid rgba(107,138,255,0.3);border-bottom:none;"></div>
<div class="mem-segment seg-heap" style="min-height:30px;border-top:none;">
<span style="font-size:0.65rem;opacity:0.6;">↑ HEAP (grows up)</span>
</div>
</div>
<div class="mem-segment seg-bss">BSS<br><span style="font-size:0.65rem;opacity:0.6;">초기화 안 된 전역변수</span></div>
<div class="mem-segment seg-data">DATA<br><span style="font-size:0.65rem;opacity:0.6;">초기화된 전역/정적 변수</span></div>
<div class="mem-segment seg-code" style="border-radius:0 0 6px 6px;">CODE (TEXT)<br><span style="font-size:0.65rem;opacity:0.6;">읽기전용 실행 코드</span></div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.65rem;color:var(--text-dim);text-align:right;margin-top:2px;">0x0000 (Low)</div>
</div>
<!-- Info panel -->
<div class="mem-info-panel">
<div style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);margin-bottom:10px;">포인터 현황</div>
<div class="ptr-indicator ptr-sp">
<span>SP (스택 포인터)</span><span id="ml-sp-val">SP = 0xFFFF</span>
</div>
<div class="ptr-indicator ptr-hp">
<span>HP (힙 포인터)</span><span id="ml-hp-val">HP = 0x4000</span>
</div>
<div class="mem-warn" id="ml-warn">스택과 힙이 충돌 위험! Stack Overflow 또는 Heap Overflow 가능성이 있습니다.</div>
<div style="margin-top:16px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);">세그먼트 설명</div>
<div style="margin-top:8px;display:flex;flex-direction:column;gap:6px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;">
<div style="display:flex;gap:8px;align-items:baseline;"><span style="color:var(--accent2);min-width:60px;">STACK</span><span style="color:var(--text-dim);">함수 호출 시 지역변수, 반환주소, 매개변수 저장</span></div>
<div style="display:flex;gap:8px;align-items:baseline;"><span style="color:var(--accent3);min-width:60px;">HEAP</span><span style="color:var(--text-dim);">malloc/new로 동적 할당. 프로그래머가 직접 관리</span></div>
<div style="display:flex;gap:8px;align-items:baseline;"><span style="color:var(--accent4);min-width:60px;">BSS</span><span style="color:var(--text-dim);">int g; 처럼 초기값 없는 전역변수 (0으로 자동초기화)</span></div>
<div style="display:flex;gap:8px;align-items:baseline;"><span style="color:var(--accent4);min-width:60px;">DATA</span><span style="color:var(--text-dim);">int g=5; 처럼 초기값 있는 전역/static 변수</span></div>
<div style="display:flex;gap:8px;align-items:baseline;"><span style="color:var(--accent);min-width:60px;">CODE</span><span style="color:var(--text-dim);">컴파일된 기계어 명령어. 읽기 전용(쓰면 segfault)</span></div>
</div>
<div class="info-text" style="margin-top:14px;">
💡 <strong>Tip:</strong> 재귀 함수를 무한히 호출하면 스택이 힙 방향으로 계속 자라다가 <code>stack overflow</code>가 발생합니다. C에서 free()를 잊으면 힙이 누수(memory leak)됩니다.
</div>
</div>
</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 3: 컨텍스트 스위칭 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="context">
<div class="section-header">
<div class="tag tag-ch6">CTX</div>
<h2>컨텍스트 스위칭 (Context Switch)</h2>
<p>CPU는 1초에 수백~수천 번 프로세스를 교체합니다. 교체할 때마다 현재 프로세스의 '상태'(레지스터, PC, 스택 포인터 등)를 PCB에 저장하고, 다음 프로세스의 상태를 복원합니다. 이 오버헤드 시간 동안 CPU는 유용한 작업을 하지 못합니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn" id="ctxAutoBtn" onclick="ctxAutoRun()">자동 실행</button>
<button class="btn" id="ctxStepBtn" onclick="ctxStep()">다음 전환 →</button>
<button class="btn danger" onclick="ctxReset()">초기화</button>
</div>
<div class="ctx-timeline-label">CPU 타임라인 (시간 →)</div>
<div class="ctx-timeline" id="ctxTimeline"></div>
<div class="ctx-legend">
<div class="ctx-legend-item"><div class="ctx-legend-dot" style="background:rgba(107,138,255,0.5);border:1px solid var(--accent3);"></div>Process A 실행</div>
<div class="ctx-legend-item"><div class="ctx-legend-dot" style="background:rgba(255,107,157,0.5);border:1px solid var(--accent2);"></div>Process B 실행</div>
<div class="ctx-legend-item"><div class="ctx-legend-dot" style="background:rgba(136,136,170,0.2);border:1px dashed var(--border);"></div>오버헤드 (비생산)</div>
</div>
<div class="ctx-pcb-row">
<div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--accent3);margin-bottom:8px;">PCB — Process A</div>
<div class="pcb-card" id="pcbA">
<div class="pcb-row"><span class="pcb-key">PID</span><span class="pcb-val" id="pcbA-pid">1</span></div>
<div class="pcb-row"><span class="pcb-key">PC</span><span class="pcb-val" id="pcbA-pc">0x0040</span></div>
<div class="pcb-row"><span class="pcb-key">SP</span><span class="pcb-val" id="pcbA-sp">0xFF80</span></div>
<div class="pcb-row"><span class="pcb-key">AX</span><span class="pcb-val" id="pcbA-ax">0x0005</span></div>
<div class="pcb-row"><span class="pcb-key">State</span><span class="pcb-val" id="pcbA-state" style="color:var(--accent);">RUNNING</span></div>
</div>
</div>
<div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--accent2);margin-bottom:8px;">PCB — Process B</div>
<div class="pcb-card" id="pcbB">
<div class="pcb-row"><span class="pcb-key">PID</span><span class="pcb-val">2</span></div>
<div class="pcb-row"><span class="pcb-key">PC</span><span class="pcb-val" id="pcbB-pc">0x00A0</span></div>
<div class="pcb-row"><span class="pcb-key">SP</span><span class="pcb-val" id="pcbB-sp">0xFE00</span></div>
<div class="pcb-row"><span class="pcb-key">AX</span><span class="pcb-val" id="pcbB-ax">0x001F</span></div>
<div class="pcb-row"><span class="pcb-key">State</span><span class="pcb-val" id="pcbB-state" style="color:var(--text-dim);">READY</span></div>
</div>
</div>
</div>
<div class="ctx-counter-row">
<div class="ctx-counter">
<div class="ctx-counter-val" id="ctxCount">0</div>
<div class="ctx-counter-label">컨텍스트 전환 횟수</div>
</div>
<div class="ctx-counter">
<div class="ctx-counter-val" id="ctxOverhead" style="color:var(--danger);">0 ms</div>
<div class="ctx-counter-label">낭비된 오버헤드</div>
</div>
<div class="ctx-counter">
<div class="ctx-counter-val" id="ctxCurrent" style="color:var(--accent3);">A</div>
<div class="ctx-counter-label">현재 실행 중인 프로세스</div>
</div>
</div>
<div class="info-text">
💡 <strong>Tip:</strong> 컨텍스트 스위치는 CPU에 저장된 레지스터 전체(수십~수백 개)를 메모리에 쓰고 읽는 작업입니다. 이 오버헤드가 크기 때문에 OS는 타임슬라이스(quantum)를 너무 짧게 설정하지 않습니다.
</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 4: 메모리 관리 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="memory">
<div class="section-header">
<div class="tag tag-ch6">ALLOC</div>
<h2>메모리 관리 (Memory Allocation)</h2>
<p>OS는 여러 프로세스에게 물리 메모리를 나눠줍니다. 프로세스들이 할당·해제를 반복하면 메모리 곳곳에 사용할 수 없는 작은 구멍들이 생기는 <em>외부 단편화(fragmentation)</em>가 발생합니다. 메모리 압축(compaction)으로 이를 해소할 수 있지만 비용이 큽니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn" onclick="memAlloc()">프로세스 할당</button>
<button class="btn" onclick="memFree()">랜덤 해제</button>
<button class="btn" onclick="memCompact()">메모리 압축</button>
<button class="btn danger" onclick="memReset()">초기화</button>
</div>
<div id="memGrid" style="display:grid;grid-template-columns:repeat(16,1fr);gap:3px;"></div>
<div class="info-text" id="memInfo">메모리 상태: 비어있음 | 단편화: 0%<br>
💡 <strong>Tip:</strong> 단편화 지수가 높을수록 비어있는 블록이 잘게 쪼개져 큰 프로세스를 할당하기 어렵습니다. 압축은 실행 중인 프로세스를 이동시켜야 하므로 비용이 큽니다.</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 5: 가상메모리 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="virtualmem">
<div class="section-header">
<div class="tag tag-ch6">VM</div>
<h2>가상메모리 (Virtual Memory)</h2>
<p>프로세스는 실제 물리 메모리보다 훨씬 큰 메모리 공간을 사용할 수 있습니다. OS는 <em>페이지 테이블</em>을 통해 가상 주소를 물리 주소로 변환합니다. 필요한 페이지가 물리 메모리에 없으면 <em>페이지 폴트(Page Fault)</em>가 발생하고 디스크에서 로드합니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn" onclick="vmAccessRandom()">랜덤 페이지 접근</button>
<button class="btn" onclick="vmAccessSequential()">순차 접근 (0→7)</button>
<button class="btn danger" onclick="vmReset()">초기화</button>
</div>
<div class="vm-layout">
<div>
<div class="vm-col-title">가상 페이지 (8개)</div>
<div class="vm-pages" id="vmPages"></div>
</div>
<div>
<div class="vm-pt-title">페이지 테이블</div>
<div class="vm-pt" id="vmPageTable"></div>
</div>
<div>
<div class="vm-col-title">물리 프레임 (4개)</div>
<div class="vm-frames" id="vmFrames"></div>
</div>
</div>
<div class="vm-stats">
<div class="vm-stat hit-stat">
<div class="vm-stat-val" id="vmHits">0</div>
<div class="vm-stat-label">PAGE HIT</div>
</div>
<div class="vm-stat fault-stat">
<div class="vm-stat-val" id="vmFaults">0</div>
<div class="vm-stat-label">PAGE FAULT</div>
</div>
<div class="vm-stat" style="text-align:center;">
<div class="vm-stat-val" id="vmHitRate" style="color:var(--accent4);">—</div>
<div class="vm-stat-label">HIT RATE</div>
</div>
</div>
<div class="info-text" id="vmInfo">가상 페이지를 클릭하거나 버튼을 눌러 접근을 시뮬레이션하세요.<br>
💡 <strong>Tip:</strong> 물리 프레임이 꽉 찼을 때 FIFO 알고리즘은 가장 먼저 들어온 페이지를 교체합니다. 실제 OS는 LRU(가장 오래 미사용)나 Clock 알고리즘을 사용합니다.</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 6: 프로세스 스케줄링 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="scheduling">
<div class="section-header">
<div class="tag tag-ch6">SCHED</div>
<h2>프로세스 스케줄링 (Process Scheduling)</h2>
<p>여러 프로세스가 CPU를 원할 때 OS는 어떤 순서로 실행할지 결정합니다. FCFS는 단순하지만 짧은 작업이 오래 기다릴 수 있고, SJF는 평균 대기 시간을 최소화하며, Round Robin은 공정성을 보장합니다.</p>
</div>
<div class="viz-box">
<div class="controls">
<button class="btn active" id="btnFCFS" onclick="setScheduler('fcfs',this)">FCFS</button>
<button class="btn" id="btnSJF" onclick="setScheduler('sjf',this)">SJF</button>
<button class="btn" id="btnRR" onclick="setScheduler('rr',this)">Round Robin (q=2)</button>
<button class="btn" onclick="runScheduler()">실행</button>
<button class="btn danger" onclick="resetScheduler()">초기화</button>
</div>
<!-- Ready Queue visualization -->
<div class="rq-wrap">
<div class="rq-title">레디 큐 (Ready Queue) — 실행 대기 중인 프로세스</div>
<div class="rq-queue" id="rqQueue">
<span style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);">스케줄러를 실행하면 레디 큐가 표시됩니다</span>
</div>
<div class="rq-cpu" style="margin-top:10px;">
<span style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);">CPU:</span>
<div class="rq-cpu-box" id="rqCpuBox">유휴</div>
<span style="font-family:'JetBrains Mono',monospace;font-size:0.75rem;color:var(--text-dim);">← 디스패처</span>
</div>
</div>
<div style="margin-bottom:16px;">
<div style="font-family:'JetBrains Mono',monospace;font-size:0.78rem;color:var(--text-dim);margin-bottom:10px;">프로세스 정보</div>
<div id="procTable" style="display:flex;flex-direction:column;gap:6px;"></div>
</div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.78rem;color:var(--text-dim);margin-bottom:8px;">Gantt 차트</div>
<div class="process-timeline" id="ganttChart"></div>
<div class="process-info" id="procStats"></div>
<div class="info-text" style="margin-top:16px;">
💡 <strong>Tip:</strong> WT(대기시간) = 반환시간 - 버스트시간. TAT(반환시간) = 완료시간 - 도착시간. SJF는 starvation(기아) 문제가 있어 짧은 작업이 계속 오면 긴 작업은 영원히 기다릴 수 있습니다.
</div>
</div>
</section>
<div class="section-divider"></div>
<!-- ═══════════════════════════════════════════════════════ -->
<!-- SECTION 7: 데드락 -->
<!-- ═══════════════════════════════════════════════════════ -->
<section id="deadlock">
<div class="section-header">
<div class="tag tag-ch6">DEADLOCK</div>
<h2>데드락 (Deadlock)</h2>
<p>두 개 이상의 프로세스가 서로 상대방이 가진 자원을 기다리며 영원히 멈추는 상태입니다. 식사하는 철학자 문제로 데드락의 발생 과정과 해결책을 시뮬레이션합니다.</p>
</div>
<div class="viz-box">
<!-- 4 Conditions Checklist -->
<div style="font-family:'JetBrains Mono',monospace;font-size:0.78rem;color:var(--text-dim);margin-bottom:10px;">데드락 4가지 필요조건 — 클릭해서 체크/해제</div>
<div class="dl-conditions">
<div class="dl-cond" id="cond0" onclick="dlToggleCond(0)">
<span class="cond-check">☐</span>
<div class="cond-num">CONDITION 01</div>
<div class="cond-name">상호배제 (Mutual Exclusion)</div>
<div class="cond-desc">자원은 한 번에 한 프로세스만 사용 가능. 포크는 한 철학자만 쥘 수 있습니다.</div>
</div>
<div class="dl-cond" id="cond1" onclick="dlToggleCond(1)">
<span class="cond-check">☐</span>
<div class="cond-num">CONDITION 02</div>
<div class="cond-name">점유 및 대기 (Hold & Wait)</div>
<div class="cond-desc">자원을 점유한 채로 다른 자원을 기다림. 왼쪽 포크를 쥔 채 오른쪽 포크를 기다립니다.</div>
</div>
<div class="dl-cond" id="cond2" onclick="dlToggleCond(2)">
<span class="cond-check">☐</span>
<div class="cond-num">CONDITION 03</div>
<div class="cond-name">비선점 (No Preemption)</div>
<div class="cond-desc">자원을 강제로 빼앗을 수 없음. 철학자가 포크를 자발적으로 내려놓을 때만 반납됩니다.</div>
</div>
<div class="dl-cond" id="cond3" onclick="dlToggleCond(3)">
<span class="cond-check">☐</span>
<div class="cond-num">CONDITION 04</div>
<div class="cond-name">순환 대기 (Circular Wait)</div>
<div class="cond-desc">P0→R1→P1→R2→...→Pn→R0 처럼 프로세스들이 원형으로 서로를 기다립니다.</div>
</div>
</div>
<div class="dl-deadlock-indicator no" id="dlCondIndicator">
4가지 조건 중 0/4 충족 — 데드락 위험 없음
</div>
<div style="margin-top:24px;">
<div class="dl-phase" id="dlPhaseBar"></div>
<div class="controls">
<button class="btn active" id="dlStartBtn" onclick="dlStart()">시뮬레이션 시작</button>
<button class="btn danger" onclick="dlReset()">초기화</button>
</div>
<div class="deadlock-canvas-wrap">
<canvas id="dlCanvas" height="360"></canvas>
<div class="deadlock-status safe" id="dlStatus">정상</div>
</div>
<div class="dl-progress-wrap"><div class="dl-progress" id="dlProgress"></div></div>
<div class="narration-log" id="narrationLog"></div>
</div>
<div class="info-text" style="margin-top:16px;">
💡 <strong>해결책:</strong> (1) 순환 대기 제거 — 홀수 철학자는 오른쪽 먼저, 짝수는 왼쪽 먼저 집기. (2) 한 번에 두 포크 모두 집거나 아무것도 안 집기 (Hold & Wait 제거). (3) 철학자 수를 N-1명으로 제한 (동시 착석 제한).
</div>
</div>
</section>
<div class="section-divider"></div>
<!-- SECTION 8: 프로세스 vs 스레드 -->
<section id="thread">
<div class="section-header">
<div class="tag tag-ch6">08 — PROCESS vs THREAD</div>
<h2>프로세스 vs 스레드</h2>
<p>프로세스는 실행 중인 프로그램의 독립적인 인스턴스이고, 스레드는 프로세스 내에서 실행되는 가장 작은 실행 단위입니다.</p>
</div>
<div class="viz-box">
<!-- 메모리 구조 비교 다이어그램 -->
<div style="display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-bottom:24px;">
<!-- 프로세스 -->
<div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.82rem;font-weight:700;color:var(--accent);margin-bottom:10px;">프로세스 A</div>
<div style="border:2px solid var(--accent);border-radius:8px;padding:12px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;">
<div style="background:rgba(0,255,170,0.08);border:1px solid rgba(0,255,170,0.3);border-radius:4px;padding:6px 10px;margin-bottom:6px;">
<div style="color:var(--accent);font-weight:600;">스레드 1</div>
<div style="color:var(--text-dim);font-size:0.68rem;">Stack · Registers · PC</div>
</div>
<div style="background:rgba(0,255,170,0.08);border:1px solid rgba(0,255,170,0.3);border-radius:4px;padding:6px 10px;margin-bottom:6px;">
<div style="color:var(--accent);font-weight:600;">스레드 2</div>
<div style="color:var(--text-dim);font-size:0.68rem;">Stack · Registers · PC</div>
</div>
<div style="border-top:1px dashed var(--border);margin:8px 0;"></div>
<div style="color:var(--text-dim);font-size:0.7rem;">공유 영역</div>
<div style="display:flex;gap:6px;flex-wrap:wrap;margin-top:6px;">
<span style="background:rgba(107,138,255,0.15);border:1px solid var(--accent3);border-radius:4px;padding:3px 8px;color:var(--accent3);font-size:0.68rem;">Code</span>
<span style="background:rgba(107,138,255,0.15);border:1px solid var(--accent3);border-radius:4px;padding:3px 8px;color:var(--accent3);font-size:0.68rem;">Data</span>
<span style="background:rgba(107,138,255,0.15);border:1px solid var(--accent3);border-radius:4px;padding:3px 8px;color:var(--accent3);font-size:0.68rem;">Heap</span>
<span style="background:rgba(107,138,255,0.15);border:1px solid var(--accent3);border-radius:4px;padding:3px 8px;color:var(--accent3);font-size:0.68rem;">Files</span>
</div>
</div>
</div>
<!-- 멀티 프로세스 -->
<div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.82rem;font-weight:700;color:var(--accent2);margin-bottom:10px;">프로세스 B (독립)</div>
<div style="border:2px solid var(--accent2);border-radius:8px;padding:12px;font-family:'JetBrains Mono',monospace;font-size:0.75rem;">
<div style="background:rgba(255,107,157,0.08);border:1px solid rgba(255,107,157,0.3);border-radius:4px;padding:6px 10px;margin-bottom:6px;">
<div style="color:var(--accent2);font-weight:600;">스레드 1 (Main)</div>
<div style="color:var(--text-dim);font-size:0.68rem;">Stack · Registers · PC</div>
</div>
<div style="border-top:1px dashed var(--border);margin:8px 0;"></div>
<div style="color:var(--text-dim);font-size:0.7rem;">독립 메모리 공간</div>
<div style="display:flex;gap:6px;flex-wrap:wrap;margin-top:6px;">
<span style="background:rgba(255,107,157,0.1);border:1px solid var(--accent2);border-radius:4px;padding:3px 8px;color:var(--accent2);font-size:0.68rem;">Code</span>
<span style="background:rgba(255,107,157,0.1);border:1px solid var(--accent2);border-radius:4px;padding:3px 8px;color:var(--accent2);font-size:0.68rem;">Data</span>
<span style="background:rgba(255,107,157,0.1);border:1px solid var(--accent2);border-radius:4px;padding:3px 8px;color:var(--accent2);font-size:0.68rem;">Heap</span>
<span style="background:rgba(255,107,157,0.1);border:1px solid var(--accent2);border-radius:4px;padding:3px 8px;color:var(--accent2);font-size:0.68rem;">Files</span>
</div>
<div style="margin-top:8px;font-size:0.68rem;color:var(--danger);">⚠ 프로세스 간 직접 메모리 접근 불가 → IPC 필요</div>
</div>
</div>
</div>
<!-- 비교 표 -->
<table style="width:100%;border-collapse:collapse;font-family:'JetBrains Mono',monospace;font-size:0.78rem;margin-bottom:20px;">
<tr>
<th style="padding:10px 14px;background:var(--surface2);color:var(--text-dim);text-align:left;border-bottom:1px solid var(--border);font-size:0.7rem;letter-spacing:1px;">항목</th>
<th style="padding:10px 14px;background:rgba(0,255,170,0.06);color:var(--accent);text-align:left;border-bottom:1px solid var(--border);">프로세스</th>
<th style="padding:10px 14px;background:rgba(107,138,255,0.06);color:var(--accent3);text-align:left;border-bottom:1px solid var(--border);">스레드</th>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);border-bottom:1px solid var(--border);">메모리</td>
<td style="padding:8px 14px;color:var(--text);border-bottom:1px solid var(--border);">독립된 메모리 공간</td>
<td style="padding:8px 14px;color:var(--text);border-bottom:1px solid var(--border);">같은 프로세스 메모리 공유</td>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);border-bottom:1px solid var(--border);">생성 비용</td>
<td style="padding:8px 14px;color:var(--danger);border-bottom:1px solid var(--border);">높음 (fork/exec)</td>
<td style="padding:8px 14px;color:var(--accent);border-bottom:1px solid var(--border);">낮음 (경량)</td>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);border-bottom:1px solid var(--border);">통신 방법</td>
<td style="padding:8px 14px;color:var(--text);border-bottom:1px solid var(--border);">IPC (파이프, 소켓, 공유메모리)</td>
<td style="padding:8px 14px;color:var(--text);border-bottom:1px solid var(--border);">공유 변수 직접 접근</td>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);border-bottom:1px solid var(--border);">격리성</td>
<td style="padding:8px 14px;color:var(--accent);border-bottom:1px solid var(--border);">높음 (하나 죽어도 영향 없음)</td>
<td style="padding:8px 14px;color:var(--danger);border-bottom:1px solid var(--border);">낮음 (하나 오류 → 전체 영향)</td>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);border-bottom:1px solid var(--border);">컨텍스트 스위칭</td>
<td style="padding:8px 14px;color:var(--danger);border-bottom:1px solid var(--border);">느림 (TLB flush 등)</td>
<td style="padding:8px 14px;color:var(--accent);border-bottom:1px solid var(--border);">빠름 (메모리 공유)</td>
</tr>
<tr>
<td style="padding:8px 14px;color:var(--text-dim);">동기화</td>
<td style="padding:8px 14px;color:var(--text);">불필요 (독립)</td>
<td style="padding:8px 14px;color:var(--accent4);">필요! (Race condition 주의)</td>
</tr>
</table>
<!-- fork/exec 시뮬레이션 -->
<div style="font-family:'JetBrains Mono',monospace;font-size:0.82rem;font-weight:700;margin-bottom:10px;">fork() / exec() 동작</div>
<div class="controls">
<button class="btn" onclick="animFork()">fork() 실행</button>
<button class="btn" onclick="animExec()">exec() 실행</button>
<button class="btn danger" onclick="resetFork()">초기화</button>
</div>
<div id="forkViz" style="font-family:'JetBrains Mono',monospace;font-size:0.8rem;padding:16px;background:var(--surface2);border-radius:8px;min-height:80px;line-height:2;"></div>
<div class="info-text" style="margin-top:16px;">
<strong style="color:var(--accent)">멀티스레딩</strong>: 하나의 프로세스에서 여러 스레드가 동시에 실행. CPU 코어를 최대 활용하지만 <strong style="color:var(--danger)">Race Condition</strong>에 주의 필요. Chrome은 탭마다 별도 프로세스(안정성↑), Node.js는 단일 스레드 + 이벤트 루프.
</div>
</div>
</section>
<div class="section-divider"></div>
<!-- SECTION 9: 동기화 -->
<section id="sync">
<div class="section-header">
<div class="tag tag-ch6">09 — SYNCHRONIZATION</div>
<h2>동기화 — Race Condition & 뮤텍스/세마포어</h2>
<p>여러 스레드가 같은 자원을 동시에 접근할 때 발생하는 문제와 해결 방법입니다. 임계구역(Critical Section)을 보호하는 것이 핵심입니다.</p>
</div>
<div class="viz-box">
<!-- Race Condition 시뮬레이션 -->
<div style="font-family:'JetBrains Mono',monospace;font-size:0.85rem;font-weight:700;margin-bottom:12px;color:var(--danger)">① Race Condition</div>
<div style="font-family:'JetBrains Mono',monospace;font-size:0.76rem;color:var(--text-dim);margin-bottom:14px;">
두 스레드가 공유 변수 counter를 동시에 증가시킬 때, 예상과 다른 결과가 나올 수 있습니다.
</div>
<div class="controls">
<button class="btn danger" onclick="runRace()">Race Condition 실행</button>
<button class="btn" onclick="runSafe()">뮤텍스로 보호 실행</button>
<button class="btn danger" onclick="resetRace()">초기화</button>
</div>
<div style="display:grid;grid-template-columns:1fr 1fr 1fr;gap:16px;margin:16px 0;">
<div style="background:var(--surface2);border:1px solid rgba(0,255,170,0.3);border-radius:8px;padding:14px;text-align:center;font-family:'JetBrains Mono',monospace;">
<div style="font-size:0.7rem;color:var(--text-dim);margin-bottom:6px;">Thread 1</div>
<div id="t1Val" style="font-size:1.6rem;font-weight:700;color:var(--accent);">-</div>
<div id="t1Status" style="font-size:0.7rem;color:var(--text-dim);margin-top:4px;">대기</div>
</div>
<div style="background:var(--surface2);border:2px solid var(--accent4);border-radius:8px;padding:14px;text-align:center;font-family:'JetBrains Mono',monospace;">
<div style="font-size:0.7rem;color:var(--text-dim);margin-bottom:6px;">공유 Counter</div>
<div id="counterVal" style="font-size:2rem;font-weight:700;color:var(--accent4);">0</div>
<div id="counterExpect" style="font-size:0.7rem;color:var(--text-dim);margin-top:4px;">기대값: -</div>
</div>
<div style="background:var(--surface2);border:1px solid rgba(255,107,157,0.3);border-radius:8px;padding:14px;text-align:center;font-family:'JetBrains Mono',monospace;">
<div style="font-size:0.7rem;color:var(--text-dim);margin-bottom:6px;">Thread 2</div>
<div id="t2Val" style="font-size:1.6rem;font-weight:700;color:var(--accent2);">-</div>
<div id="t2Status" style="font-size:0.7rem;color:var(--text-dim);margin-top:4px;">대기</div>
</div>
</div>
<div id="raceLog" style="font-family:'JetBrains Mono',monospace;font-size:0.72rem;background:var(--surface2);border-radius:8px;padding:12px;max-height:140px;overflow-y:auto;color:var(--text-dim);line-height:1.9;"></div>
<!-- Mutex / Semaphore -->
<div style="border-top:1px solid var(--border);padding-top:24px;margin-top:24px;">
<div style="font-family:'JetBrains Mono',monospace;font-size:0.85rem;font-weight:700;margin-bottom:12px;color:var(--accent)">② 뮤텍스 vs 세마포어</div>
<div style="display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-bottom:16px;">
<div style="background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:16px;font-family:'JetBrains Mono',monospace;font-size:0.78rem;">
<div style="color:var(--accent);font-weight:700;margin-bottom:8px;">Mutex (상호배제)</div>
<div style="color:var(--text-dim);font-size:0.72rem;line-height:1.8;">
· 값: 0 또는 1 (이진 잠금)<br>
· 소유자가 lock/unlock<br>
· 한 번에 1개 스레드만 진입<br>
· 사용: 임계구역 보호<br>
</div>
<div id="mutexViz" style="margin-top:12px;display:flex;gap:8px;align-items:center;flex-wrap:wrap;"></div>
</div>
<div style="background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:16px;font-family:'JetBrains Mono',monospace;font-size:0.78rem;">
<div style="color:var(--accent3);font-weight:700;margin-bottom:8px;">Semaphore (세마포어)</div>
<div style="color:var(--text-dim);font-size:0.72rem;line-height:1.8;">
· 값: 0~N (정수 카운터)<br>
· 여러 스레드가 사용 가능<br>
· wait(P) / signal(V) 연산<br>
· 사용: 자원 개수 제한<br>
</div>
<div id="semViz" style="margin-top:12px;display:flex;gap:8px;align-items:center;flex-wrap:wrap;"></div>
</div>
</div>
<div class="controls">
<button class="btn" onclick="mutexLock()">Mutex Lock</button>
<button class="btn" onclick="mutexUnlock()">Mutex Unlock</button>
<span style="font-family:'JetBrains Mono',monospace;font-size:0.8rem;color:var(--text-dim);margin:0 8px;">|</span>
<button class="btn" onclick="semWait()">Semaphore wait()</button>
<button class="btn" onclick="semSignal()">Semaphore signal()</button>
<button class="btn danger" onclick="resetSync()">초기화</button>
</div>
<div id="syncLog" style="font-family:'JetBrains Mono',monospace;font-size:0.72rem;background:var(--surface2);border-radius:8px;padding:12px;max-height:100px;overflow-y:auto;color:var(--text-dim);line-height:1.9;margin-top:12px;"></div>
</div>
<div class="info-text" style="margin-top:16px;">
<strong style="color:var(--accent)">임계구역 (Critical Section)</strong>: 공유 자원에 접근하는 코드 구간. 보호를 위해 <strong style="color:var(--accent4)">상호배제(Mutex)</strong>, <strong style="color:var(--accent3)">세마포어</strong>, <strong style="color:var(--accent2)">모니터</strong> 사용.
교착상태(Deadlock)를 피하려면 락 획득 순서를 일관되게 유지해야 합니다.
</div>
</div>
</section>
<footer>CS Visualizer · <a href="index.html" style="color:var(--accent);text-decoration:none;">목차로 돌아가기</a></footer>
<script>
/* ══════════════════════════════════════════════════════════
HELPERS
══════════════════════════════════════════════════════════ */
function sl(ms) { return new Promise(r => setTimeout(r, ms)); }
function rnd(a, b) { return Math.floor(Math.random() * (b - a + 1)) + a; }
function hex(n) { return '0x' + n.toString(16).toUpperCase().padStart(4, '0'); }
/* ══════════════════════════════════════════════════════════
SECTION 1: PROCESS STATE DIAGRAM
══════════════════════════════════════════════════════════ */
const PS_STATES = ['new','ready','running','waiting','terminated'];
const PS_COLORS = {
new: '#8888aa',
ready: 'var(--accent3)',
running: 'var(--accent)',
waiting: 'var(--accent4)',
terminated: 'var(--danger)'
};
const PS_BADGE_STYLES = {
new: 'background:rgba(136,136,170,0.15);color:#8888aa;',
ready: 'background:rgba(107,138,255,0.15);color:var(--accent3);',
running: 'background:rgba(0,255,170,0.15);color:var(--accent);',
waiting: 'background:rgba(255,170,0,0.15);color:var(--accent4);',
terminated: 'background:rgba(255,68,102,0.15);color:var(--danger);'
};
const PS_LABELS = {
new:'NEW', ready:'READY', running:'RUNNING', waiting:'WAITING', terminated:'TERMINATED'
};
let psProcs = [
{ pid: 'P1', name: 'chrome', state: 'running', priority: 'HIGH', time: 0 },
{ pid: 'P2', name: 'node', state: 'ready', priority: 'NORMAL', time: 0 },
{ pid: 'P3', name: 'vim', state: 'waiting', priority: 'LOW', time: 0 },
];
let psSelected = 0;
const PS_NODE_POSITIONS = {
new: { x: 0.08, y: 0.5 },
ready: { x: 0.32, y: 0.25 },
running: { x: 0.58, y: 0.25 },
waiting: { x: 0.58, y: 0.72 },
terminated: { x: 0.82, y: 0.5 },
};
const PS_EDGES = [
{ from:'new', to:'ready', label:'생성(fork)', curve: 0 },
{ from:'ready', to:'running', label:'dispatch', curve: -0.15 },
{ from:'running', to:'ready', label:'타임슬라이스 만료', curve: -0.15 },
{ from:'running', to:'waiting', label:'I/O 요청', curve: 0 },
{ from:'waiting', to:'ready', label:'I/O 완료', curve: 0 },
{ from:'running', to:'terminated', label:'exit()', curve: 0 },
];
let psCanvas, psCtx;
let psActiveEdge = null;
function psInit() {
psCanvas = document.getElementById('psCanvas');
psCtx = psCanvas.getContext('2d');
psResize();
window.addEventListener('resize', psResize);
psRenderTable();
}
function psResize() {
const wrap = psCanvas.parentElement;
psCanvas.width = wrap.clientWidth;
psCanvas.height = 280;
psDrawDiagram();
}
function psDrawDiagram() {
if (!psCtx) return;
const w = psCanvas.width, h = psCanvas.height;
psCtx.clearRect(0, 0, w, h);
// draw edges
PS_EDGES.forEach(e => {
const fp = PS_NODE_POSITIONS[e.from];
const tp = PS_NODE_POSITIONS[e.to];
const fx = fp.x * w, fy = fp.y * h;
const tx = tp.x * w, ty = tp.y * h;
const isActive = psActiveEdge && psActiveEdge.from === e.from && psActiveEdge.to === e.to;
psDrawArrow(fx, fy, tx, ty, e.curve, e.label, isActive);
});
// draw nodes
PS_STATES.forEach(s => {
const p = PS_NODE_POSITIONS[s];
const x = p.x * w, y = p.y * h;
const isCurrentState = psProcs[psSelected] && psProcs[psSelected].state === s;
psDrawNode(x, y, PS_LABELS[s], s, isCurrentState);
});
}
function psDrawNode(x, y, label, state, highlight) {
const nw = 90, nh = 36;
const colors = {
new:'#8888aa', ready:'#6b8aff', running:'#00ffaa',
waiting:'#ffaa00', terminated:'#ff4466'
};
const col = colors[state];
psCtx.save();
// shadow glow for active
if (highlight) {
psCtx.shadowColor = col;
psCtx.shadowBlur = 18;
}
// box
psCtx.beginPath();
psCtx.roundRect(x - nw/2, y - nh/2, nw, nh, 6);
psCtx.fillStyle = highlight ? col + '33' : col + '18';
psCtx.strokeStyle = col;
psCtx.lineWidth = highlight ? 2.5 : 1.5;
psCtx.fill();
psCtx.stroke();
psCtx.shadowBlur = 0;
// label
psCtx.fillStyle = col;
psCtx.font = (highlight ? 'bold ' : '') + '11px JetBrains Mono';
psCtx.textAlign = 'center';
psCtx.textBaseline = 'middle';
psCtx.fillText(label, x, y);
psCtx.restore();
}
function psDrawArrow(fx, fy, tx, ty, curve, label, isActive) {
const mx = (fx + tx) / 2, my = (fy + ty) / 2;
const dx = tx - fx, dy = ty - fy;
const len = Math.sqrt(dx*dx + dy*dy);
const cx = mx - dy * curve * 0.5, cy = my + dx * curve * 0.5;
psCtx.save();
psCtx.beginPath();
psCtx.moveTo(fx, fy);
psCtx.quadraticCurveTo(cx, cy, tx, ty);
psCtx.strokeStyle = isActive ? '#00ffaa' : 'rgba(136,136,170,0.45)';
psCtx.lineWidth = isActive ? 2.5 : 1.2;
psCtx.setLineDash(isActive ? [] : [5, 3]);
psCtx.stroke();
psCtx.setLineDash([]);
// arrowhead
const angle = Math.atan2(ty - cy, tx - cx);
psCtx.beginPath();
psCtx.moveTo(tx, ty);
psCtx.lineTo(tx - 9 * Math.cos(angle - 0.4), ty - 9 * Math.sin(angle - 0.4));
psCtx.lineTo(tx - 9 * Math.cos(angle + 0.4), ty - 9 * Math.sin(angle + 0.4));
psCtx.closePath();
psCtx.fillStyle = isActive ? '#00ffaa' : 'rgba(136,136,170,0.5)';
psCtx.fill();
// label
const lx = cx + (mx - cx) * 0.4, ly = cy + (my - cy) * 0.4;
psCtx.font = '9px JetBrains Mono';
psCtx.textAlign = 'center';
psCtx.textBaseline = 'middle';
psCtx.fillStyle = isActive ? '#00ffaa' : '#8888aa';
psCtx.fillText(label, lx, ly - 8);
psCtx.restore();
}
function psUpdateStateCards() {
const state = psProcs[psSelected] ? psProcs[psSelected].state : null;
PS_STATES.forEach(s => {
const card = document.getElementById('sc-' + s);
card.className = 'state-card' + (s === state ? ' active-' + s : '');
});
}
function psRenderTable() {
const tbody = document.getElementById('psTableBody');
tbody.innerHTML = psProcs.map((p, i) => {
const style = PS_BADGE_STYLES[p.state] || '';
const rowStyle = i === psSelected
? 'background:rgba(107,138,255,0.07);border-left:3px solid var(--accent3);'
: 'cursor:pointer;border-left:3px solid transparent;';
return `<tr style="${rowStyle}" onclick="psSelectProc(${i})">
<td style="font-family:'JetBrains Mono',monospace;color:var(--accent3);">${p.pid}</td>
<td style="font-family:'JetBrains Mono',monospace;">${p.name}</td>
<td><span class="state-badge" style="${style}">${PS_LABELS[p.state]}</span></td>
<td style="font-family:'JetBrains Mono',monospace;color:var(--text-dim);">${p.priority}</td>
<td style="font-family:'JetBrains Mono',monospace;color:var(--text-dim);">${p.time}ms</td>
</tr>`;
}).join('');
}
function psSelectProc(i) {
psSelected = i;
psRenderTable();
psUpdateStateCards();
psDrawDiagram();
}
function psSpawnProcess() {
const names = ['bash','python','nginx','mysql','redis','java','go-bin','rust-app'];
const priorities = ['HIGH','NORMAL','LOW'];
const pid = 'P' + (psProcs.length + 1);
psProcs.push({ pid, name: names[rnd(0,names.length-1)], state:'new', priority: priorities[rnd(0,2)], time: 0 });
psSelected = psProcs.length - 1;
psRenderTable();
psUpdateStateCards();
psDrawDiagram();
}
async function psTransition(type) {
if (!psProcs[psSelected]) return;
const p = psProcs[psSelected];
const transitions = {
ready_to_run: { from:'ready', to:'running' },
io_request: { from:'running', to:'waiting' },
io_done: { from:'waiting', to:'ready' },
timeslice: { from:'running', to:'ready' },
terminate: { from:'running', to:'terminated' },
};
const t = transitions[type];
if (!t) return;
if (p.state !== t.from) {
// auto-fix state if possible
if (type === 'ready_to_run' && p.state === 'new') {
p.state = 'ready';
} else {
return;
}
}
psActiveEdge = { from: t.from, to: t.to };
psDrawDiagram();
await sl(600);
p.state = t.to;
p.time += rnd(10, 150);
psActiveEdge = null;
psDrawDiagram();
psRenderTable();
psUpdateStateCards();
}
/* ══════════════════════════════════════════════════════════
SECTION 2: MEMORY LAYOUT
══════════════════════════════════════════════════════════ */
let mlStackFrames = [];
let mlHeapBlocks = [];
const ML_MAX_STACK = 6;
const ML_MAX_HEAP = 5;
function mlUpdatePointers() {
const sp = 0xFFFF - mlStackFrames.length * 0x180;
const hp = 0x4000 + mlHeapBlocks.length * 0x200;
document.getElementById('ml-sp-val').textContent = 'SP = ' + hex(sp);
document.getElementById('ml-hp-val').textContent = 'HP = ' + hex(hp);
const gap = sp - hp;
const gapPct = Math.max(0, Math.round(gap / (0xFFFF - 0x4000) * 100));
document.getElementById('ml-gap-pct').textContent = '여유: ' + gapPct + '%';
const warn = document.getElementById('ml-warn');
if (gapPct < 20) {
warn.style.display = 'block';
} else {
warn.style.display = 'none';
}
}
function mlRenderStack() {
const el = document.getElementById('ml-stack-frames');
el.innerHTML = mlStackFrames.slice().reverse().map(f =>
`<div class="stack-frame">${f.name}() <span style="opacity:0.5;font-size:0.65rem;">ret=${hex(f.ret)} | local=${f.local}B</span></div>`
).join('');
}
function mlRenderHeap() {
const el = document.getElementById('ml-heap-blocks');
el.innerHTML = mlHeapBlocks.map(b =>
`<div class="heap-block">${hex(b.addr)}: malloc(${b.size}B)</div>`
).join('');
}
function mlPushStack() {
if (mlStackFrames.length >= ML_MAX_STACK) return;
const fns = ['main','renderPage','processInput','fetchData','parseJSON','calcHash','sortItems'];
const fn = fns[mlStackFrames.length % fns.length];
mlStackFrames.push({ name: fn, ret: rnd(0x1000, 0x9FFF), local: rnd(8, 64) });
mlRenderStack();
mlUpdatePointers();
}
function mlPopStack() {
if (mlStackFrames.length === 0) return;
mlStackFrames.pop();
mlRenderStack();
mlUpdatePointers();
}
function mlMalloc() {
if (mlHeapBlocks.length >= ML_MAX_HEAP) return;
const sizes = [16, 32, 64, 128, 256, 512];
const size = sizes[rnd(0, sizes.length-1)];
const addr = 0x4000 + mlHeapBlocks.length * 0x200;
mlHeapBlocks.push({ addr, size });
mlRenderHeap();
mlUpdatePointers();
}
function mlFree() {
if (mlHeapBlocks.length === 0) return;
mlHeapBlocks.pop();