feat: add 180 questions (90 sc + 90 fb) for networking subtopics

Cover 9 subtopics from the computer networking documentation:
- http-handshake: TCP/TLS/HTTP2/HTTP3 handshakes
- http-connection-cost: connection resource overhead & million concurrency
- connection-pooling: pool reuse, HTTP/1.1 vs HTTP/2
- http-keepalive: Keep-Alive principle, head-of-line blocking
- keepalive-scenarios: when to enable/disable Keep-Alive
- domain-sharding: HTTP/1.1 hack, HTTP/2 obsolescence
- cdn: edge nodes, caching, DDoS protection
- cors: same-origin policy, preflight requests
- go-build-strip: -s -w flags, binary size optimization

topics/networking/go-build-strip/fill_blank.json

@@ -0,0 +1,200 @@
+{
+  "topic": "go-build-strip",
+  "type": "fill_blank",
+  "schema_version": "1.0.0",
+  "generated": "2026-09-02T21:20:00+08:00",
+  "questions": [
+    {
+      "id": "fb-001",
+      "type": "fill_blank",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "编译",
+        "符号表"
+      ],
+      "question": "使用 go build -____ 命令可以剥离 Go 二进制文件中的符号表（symbol table），从而减小文件体积。",
+      "answer": [
+        "s",
+        "-s"
+      ],
+      "answer_rule": "any",
+      "explanation": "-s 标志告诉 Go 链接器在生成二进制文件时不写入符号表。符号表包含了所有函数名、变量名、类型名等调试信息，生产环境中通常不需要。去掉符号表后，go tool nm 等工具将无法列出符号，二进制体积也会减小。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-002",
+      "type": "fill_blank",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "编译",
+        "DWARF",
+        "调试信息"
+      ],
+      "question": "使用 go build -____ 命令可以剥离 DWARF 调试信息，进一步减小 Go 二进制文件体积。",
+      "answer": [
+        "w",
+        "-w"
+      ],
+      "answer_rule": "any",
+      "explanation": "-w 标志会去掉 DWARF（Debugging With Attributed Record Formats）调试信息。DWARF 是一种标准化的调试数据格式，包含了源码行号、局部变量、类型信息等。去掉 DWARF 后，dlv（Delve）等调试器将无法正常工作，go tool addr2line 也无法将地址翻译为行号。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-003",
+      "type": "fill_blank",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "体积优化"
+      ],
+      "question": "生产环境构建 Go 二进制时，推荐使用 go build -s -____ 组合标志，同时剥离符号表和 DWARF 调试信息以实现体积最小化。",
+      "answer": [
+        "w"
+      ],
+      "answer_rule": "all",
+      "explanation": "-s 和 -w 组合使用可以最大程度地减小二进制体积。-s 去掉符号表，-w 去掉 DWARF 调试信息，两者独立且互补。通常可将二进制体积减少约 20%-30%。Go 编译器支持这两个标志独立或组合使用。注意：这个组合一旦应用，后续反查行号信息将不可用。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-004",
+      "type": "fill_blank",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "体积优化"
+      ],
+      "question": "使用 -s -w 编译标志对 Go 二进制进行体积优化，通常可以将文件大小减少约____。",
+      "answer": [
+        "20-30%",
+        "20%到30%",
+        "20%-30%"
+      ],
+      "answer_rule": "any",
+      "explanation": "根据实际测试，-s -w 组合通常能使 Go 二进制体积减少 20%-30%。具体比例取决于原始二进制中符号表和调试信息的占比。一般来说，包含大量函数和类型的大型项目减小效果更明显。例如一个原本 20MB 的 Go 二进制，去掉后可能只有 14-16MB。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-005",
+      "type": "fill_blank",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "panic",
+        "堆栈信息"
+      ],
+      "question": "使用 -s -w 编译的 Go 程序在发生 panic 时，堆栈跟踪信息中只能显示____名，而无法显示完整的源码路径。",
+      "answer": [
+        "文件",
+        "file",
+        "文件名"
+      ],
+      "answer_rule": "any",
+      "explanation": "因为 -w 去掉了 DWARF 调试信息，panic 的堆栈跟踪虽然仍能显示函数名和文件名（这些信息被嵌入在 Go 运行时的 pclntab 中，与 DWARF 无关），但无法显示完整的源码绝对路径。函数名因为已编入 pclntab（Program Counter Line Table）所以仍然可用，但行号和路径信息不完整。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-006",
+      "type": "fill_blank",
+      "difficulty": 4,
+      "tags": [
+        "Go",
+        "pprof",
+        "性能分析"
+      ],
+      "question": "对使用 -s -w 编译的 Go 二进制文件运行 pprof 进行性能分析时，函数调用栈中只会显示内存____，而无法显示具体的函数名和行号信息。",
+      "answer": [
+        "地址",
+        "address"
+      ],
+      "answer_rule": "any",
+      "explanation": "pprof 在分析 profiling 数据时需要符号信息来将内存地址翻译为函数名+行号。如果二进制用了 -s 去掉符号表，pprof 就无法解析这些地址，只能显示原始的十六进制地址。即使只用了 -w 去 DWARF，pprof 仍能显示函数名（符号表还在），只是没有行号。要让 pprof 正常工作，最好保存未 strip 的调试版本。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-007",
+      "type": "fill_blank",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "ldflags",
+        "编译时注入"
+      ],
+      "question": "使用 go build -ldflags \"-X ____.version=1.0.0\" 可以在编译时注入版本号等变量，这与 -s -w 组合使用互不影响。",
+      "answer": [
+        "main",
+        "包路径"
+      ],
+      "answer_rule": "any",
+      "explanation": "-ldflags \"-X importpath.name=value\" 用于在编译时设置 string 类型的包级变量值。完整路径格式为 \"fully/qualified/package.Path\"。例如 main 包中的 version 变量：-ldflags \"-X main.version=1.0.0\"。这个操作通过链接器完成，与 -s -w 的符号剥离独立——因为 -X 是在编译时直接将值写入二进制数据段，不需要运行时符号表参与。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-008",
+      "type": "fill_blank",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "开发环境",
+        "调试"
+      ],
+      "question": "在本地开发和调试阶段，构建 Go 程序时____使用 -s -w 标志，以保留完整的调试信息便于使用 Delve 调试器和 pprof 工具。",
+      "answer": [
+        "不应该",
+        "不建议",
+        "不要"
+      ],
+      "answer_rule": "any",
+      "explanation": "本地开发阶段保留调试信息至关重要。Delve（dlv）调试器依赖 DWARF 信息来设置断点、查看变量值、单步调试；pprof 依赖符号表来解析函数名和行号。如果开发时用了 -s -w，调试体验会严重下降。最佳实践：开发/测试环境不 strip，仅在 CI/CD 的生产构建中使用 -s -w。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-009",
+      "type": "fill_blank",
+      "difficulty": 4,
+      "tags": [
+        "Go",
+        "addr2line",
+        "调试"
+      ],
+      "question": "当使用 -s -w 编译的程序 panic 输出中包含十六进制地址时，可使用 go tool ____ 反查对应的源码文件和行号，前提是能找到对应的未 strip 二进制。",
+      "answer": [
+        "addr2line"
+      ],
+      "answer_rule": "all",
+      "explanation": "go tool addr2line 接收二进制文件和地址列表，输出对应的源码文件和行号。但它需要未 strip 的二进制（包含 DWARF 信息）作为输入。因此生产中如果要保留事后调试能力，需要在构建时同时保存 strip 和未 strip 两个版本。未 strip 版本用于事后分析，strip 版本用于部署。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "fb-010",
+      "type": "fill_blank",
+      "difficulty": 5,
+      "tags": [
+        "Go",
+        "Rust",
+        "Java",
+        "跨语言对比"
+      ],
+      "question": "在 Rust 中通过 Cargo.toml 的 [profile.release] 设置 strip = true 可实现类似 Go 的 -s 效果；在 Java 中，____/R8 等工具通过代码缩减和混淆实现类似的二进制体积优化。",
+      "answer": [
+        "ProGuard"
+      ],
+      "answer_rule": "all",
+      "explanation": "不同语言都有二进制体积优化手段：Go 用 -s -w 剥离符号和调试信息；Rust 在 Cargo.toml 中设置 strip = true 或使用 strip 命令，效果类似；Java 使用 ProGuard（开源）或 R8（Android 官方，Google 开发的 ProGuard 替代品）进行 tree-shaking（移除未使用的类和方法）、混淆和优化。虽然原理不同（Go/Rust 是剥离元数据，Java 是缩减代码），但目标一致——减小部署体积。其他语言也有类似工具：C/C++ 的 strip 命令、.NET 的 PublishTrimmed 等。",
+      "source": null,
+      "related": []
+    }
+  ]
+}

topics/networking/go-build-strip/meta.json

@@ -0,0 +1,42 @@
+{
+  "slug": "go-build-strip",
+  "name": "Go Build Strip",
+  "description": "",
+  "tags": [
+    "DWARF",
+    "Go",
+    "Java",
+    "Rust",
+    "addr2line",
+    "ldflags",
+    "panic",
+    "pprof",
+    "体积优化",
+    "堆栈信息",
+    "开发环境",
+    "性能分析",
+    "符号表",
+    "编译",
+    "编译时注入",
+    "调试",
+    "调试信息",
+    "跨语言对比"
+  ],
+  "difficulty_range": [
+    2,
+    5
+  ],
+  "schema_version": "1.0.0",
+  "updated": "2026-09-02",
+  "question_files": [
+    "single_choice",
+    "fill_blank"
+  ],
+  "stats": {
+    "total": 20,
+    "by_type": {
+      "single_choice": 10,
+      "fill_blank": 10
+    }
+  }
+}

topics/networking/go-build-strip/single_choice.json

@@ -0,0 +1,218 @@
+{
+  "topic": "go-build-strip",
+  "type": "single_choice",
+  "schema_version": "1.0.0",
+  "generated": "2026-09-02T21:20:00+08:00",
+  "questions": [
+    {
+      "id": "sc-001",
+      "type": "single_choice",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "编译",
+        "-s"
+      ],
+      "question": "Go 编译标志 -s 的作用是什么？",
+      "options": {
+        "A": "启用安全模式",
+        "B": "剥离符号表（函数名、变量名等调试符号）",
+        "C": "启用静态编译",
+        "D": "开启优化"
+      },
+      "answer": "B",
+      "explanation": "-s 标志剥离符号表（函数名、变量名等调试符号），-w 标志剥离 DWARF 调试信息。-s -w 组合体积最小化，最适合发布部署。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-002",
+      "type": "single_choice",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "-w"
+      ],
+      "question": "Go 编译标志 -w 的作用是什么？",
+      "options": {
+        "A": "剥离符号表",
+        "B": "剥离 DWARF 调试信息（gdb/lldb 所需的详细信息）",
+        "C": "启用警告",
+        "D": "开启 Web 支持"
+      },
+      "answer": "B",
+      "explanation": "-w 标志剥离 DWARF 调试信息，这是 gdb/lldb 等调试器所需的详细信息。剥离后无法用 gdb 调试。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-003",
+      "type": "single_choice",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "体积"
+      ],
+      "question": "使用 -s 标志编译后，二进制体积大约能减少多少？",
+      "options": {
+        "A": "5-10%",
+        "B": "20-30%",
+        "C": "50-60%",
+        "D": "70-80%"
+      },
+      "answer": "B",
+      "explanation": "使用 -s 标志剥离符号表后，二进制体积大约能减少 20-30%。实际节省取决于程序复杂度。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-004",
+      "type": "single_choice",
+      "difficulty": 4,
+      "tags": [
+        "Go",
+        "编译",
+        "panic"
+      ],
+      "question": "使用 -s 标志后，panic 堆栈输出会有什么变化？",
+      "options": {
+        "A": "完全看不到函数名",
+        "B": "函数名还在，但完整源码路径丢失",
+        "C": "没有变化",
+        "D": "只显示地址"
+      },
+      "answer": "B",
+      "explanation": "使用 -s 剥离符号表后，函数名还在，但完整源码路径丢失。例如从 /home/user/app/main.go:42 变成 main.go:42。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-005",
+      "type": "single_choice",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "pprof"
+      ],
+      "question": "剥离符号表后，go tool pprof 会显示什么？",
+      "options": {
+        "A": "完整的函数名",
+        "B": "只有地址（如 0x4a3b20）",
+        "C": "错误信息",
+        "D": "没有变化"
+      },
+      "answer": "B",
+      "explanation": "剥离符号表后 pprof 只显示地址（如 0x4a3b20），无法定位到具体函数。线上排查性能问题时非常痛苦。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-006",
+      "type": "single_choice",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "编译",
+        "生产环境"
+      ],
+      "question": "生产环境发布 Go 程序时应该使用什么编译标志？",
+      "options": {
+        "A": "不加任何标志",
+        "B": "-s -w",
+        "C": "只用 -w",
+        "D": "只用 -s"
+      },
+      "answer": "B",
+      "explanation": "生产环境发布应该使用 -s -w 组合，体积最小化，最适合发布部署。同时可以结合 -ldflags 注入版本号等构建信息。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-007",
+      "type": "single_choice",
+      "difficulty": 4,
+      "tags": [
+        "Go",
+        "编译",
+        "-ldflags"
+      ],
+      "question": "go build -ldflags=\"-s -w -X main.Version=1.0\" 中 -X 的作用是什么？",
+      "options": {
+        "A": "设置编译器参数",
+        "B": "在剥离调试信息的同时注入编译时变量",
+        "C": "启用交叉编译",
+        "D": "设置输出文件名"
+      },
+      "answer": "B",
+      "explanation": "-X 用于在编译时注入变量值，可以同时剥离调试信息（-s -w）和注入版本号、构建时间等信息。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-008",
+      "type": "single_choice",
+      "difficulty": 3,
+      "tags": [
+        "Go",
+        "编译",
+        "调试"
+      ],
+      "question": "以下哪种场景不应该使用 -s 标志？",
+      "options": {
+        "A": "生产环境部署",
+        "B": "CI/CD 构建产物",
+        "C": "本地开发调试",
+        "D": "嵌入式/IoT"
+      },
+      "answer": "C",
+      "explanation": "本地开发调试需要完整调试信息，不应该使用 -s 标志。生产环境部署、CI/CD 构建产物、嵌入式/IoT 都适合使用 -s -w。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-009",
+      "type": "single_choice",
+      "difficulty": 4,
+      "tags": [
+        "Go",
+        "编译",
+        "addr2line"
+      ],
+      "question": "使用 -s -w 后线上出问题，如何通过地址反查行号？",
+      "options": {
+        "A": "go tool pprof",
+        "B": "go tool addr2line",
+        "C": "go tool trace",
+        "D": "go tool vet"
+      },
+      "answer": "B",
+      "explanation": "如果保留了构建时生成的 debug info 备份，可以用 go tool addr2line 通过地址反查行号。这是 -s -w 后排查问题的方法之一。",
+      "source": null,
+      "related": []
+    },
+    {
+      "id": "sc-010",
+      "type": "single_choice",
+      "difficulty": 2,
+      "tags": [
+        "Go",
+        "编译",
+        "语言对比"
+      ],
+      "question": "以下哪种语言有类似 Go -s -w 的功能？",
+      "options": {
+        "A": "Python",
+        "B": "Rust（strip = true in Cargo.toml）",
+        "C": "JavaScript",
+        "D": "Shell"
+      },
+      "answer": "B",
+      "explanation": "Rust 在 Cargo.toml 中设置 strip = true 可以剥离调试信息，类似 Go 的 -s -w。C/C++ 有 strip 命令，Java 有 ProGuard/R8。",
+      "source": null,
+      "related": []
+    }
+  ]
+}