跟讀練習: Cache Systems Every Developer Should Know - 通過影片學習英語口語
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Caching is a common technique in modern computing to enhance system performance and reduce response time.
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From the front end to the back end, caching plays a crucial role in improving the efficiency of various applications and systems.
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A typical system architecture involves several layers of caching.
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At each layer, there are multiple strategies and mechanisms for caching data, depending on the requirements and the constraints of the specific application.
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Before diving into a typical system architecture, let's zoom in and look at how prevalent caching is within each computer itself.
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Let's first look at the computer hardware.
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The most common hardware caches are L1, L2, and L3 caches.
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L1 cache is the smallest and fastest cache, typically integrated into the CPU itself.
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It stores frequently accessed data and instructions, allowing the CPU to quickly access them without having to fetch them from slower memory.
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L2 cache is larger but slower than L1 cache, and is typically located on the CPU die.
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L3 cache is even larger and slower than L2 cache, and is often shared between multiple CPU cores.
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Another common hardware cache is the Translation Look -Aside Buffer, or TLB.
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It stores recently used virtual to physical address translations.
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It is used by the CPU to quickly translate virtual memory addresses to physical memory addresses, reducing the time needed to access data from memory.
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At the operating system level, there are PageCache and other file system caches.
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PageCache is managed by the operating system and resides in main memory.
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It is used to store recently used disk blocks in memory.
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When a program requests data from the disk, the operating system can quickly retrieve the data from memory instead of reading it from disk.
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There are other caches managed by the operating system such as the iNode cache.
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These caches are used to speed up file system operations by
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reducing the number of disk accesses required to access files and directories.
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Now let's zoom out and look at how caching is used in a typical application system architecture.
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On the application front end, web browsers can cache HTTP responses to enable faster retrieval of data.
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When we request data over HTTP for the first time and it is returned with an expiration policy in the HTTP header.
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We request the same data again, and the browser returns the data from its cache if available.
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Content delivery network, or CDNs, are widely used to improve the delivery of static content,
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such as images, videos, and other web access.
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One of the ways that CDNs speed up content delivery is through caching.
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When a user requests contents from a CDN, the CDN network looks for the requested content in its cache.
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If the content is not already in the cache, the CDN fetches it from the origin server and caches it on its edge servers.
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When another user requests the same content, the CDN can deliver the content directly from its cache,
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eliminating the need to fetch it from the origin server again.
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Some load balancers can cache resources to reduce the load on back -end servers.
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When a user requests content from a server behind a load balancer,
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the load balancer can cache the response and serve it directly to future users who request the same content.
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This can improve response times and reduce the load on back -end servers.
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Caching does not always have to be in memory.
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In messaging infrastructure, message brokers such as Kafka can cache a massive amount of messages on disk.
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This allows consumers to retrieve the messages at their own pace.
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The messages can be cached for a long period of time based on the retention policy.
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Distributed caches such as Redis can store key value pairs in memory, providing high read -write performance compared to traditional databases.
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Full text search engines, such as Elasticsearch, can index data for document search and log search,
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providing quick and efficient access to specific data.
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Even within the database, there are multiple levels of caching available.
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Data is typically written to a write -ahead log before being indexed in a B -tree.
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The buffer pool is a memory area used to cache query results, while materialized views can pre -compute query results for faster performance.
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The transaction log records all transactions and updates to the database, while the replication log tracks the replication state in a database cluster.
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Overall, caching data is an essential technique for optimizing system performance and reducing response time.
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From the front end to the back end, there are many layers of caching to improve the efficiency of various applications and systems.
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本課的詞彙與口語要點
這節口語課以影片“Cache Systems Every Developer Should Know”為素材。 影片中反覆出現的詞有:cache, caching, memory, content, request。 這段影片共有 53 個句子、802 個單詞可供跟讀。 講話部分時長為 5:37。 說話人語速平穩,每分鐘約 143 個詞,很適合跟讀。 只有 75% 的單詞屬於英語最常用的 3,000 詞,詞彙難度較高。
影片中的重點詞彙
影片中 15 個值得學習的單詞,附發音和釋義:
| 單詞 | 發音 | 釋義 |
|---|---|---|
| cache 名詞 | /kæʃ/ | 快取 /快取, 快取 |
| server 名詞 | /ˈsɝvɚ/ | 伺服器 /伺服器, 伺服器 |
| disk 名詞 | /dɪsk/ | 圓盤 /圓盤 |
| database 名詞 | /ˈdeɪtəˌbeɪs/ | 資料庫 /資料庫 |
| architecture 名詞 | /ˈɑː.kɪˌtɛk.t͡ʃə/ | 建築 /建築, 建築學 /建築學 |
| layer 名詞 | /ˈleɪ̯ɚ/ | 層 /層 |
| hardware 名詞 | /ˈhɑɹdˌwɛɹ/ | 硬體, 硬體 /硬體 |
| fetch 動詞 | /fɛt͡ʃ/ | 取 |
| technique 名詞 | /tɛkˈniːk/ | 技術 /技術, 技巧 |
| efficiency 名詞 | /ɪˈfɪʃ.ən.si/ | 效率, 效能 |
| transaction 名詞 | /tɹænˈzækʃən/ | 處理 /處理 |
| retrieve 動詞 | /ɹɪˈtɹiːv/ | 重拾 |
| query 名詞 | /ˈkwɪɹ.i/ | 問題 /問題, 質問 /質問 |
| topic 名詞 | /ˈtɑpɪk/ | 主題 /主題, 話題 /話題 |
| infrastructure 名詞 | /ˈɪnfɹəˌstɹʌkt͡ʃə/ | 基礎設施 /基礎設施 |
影片中出現的短語動詞
| 單詞 | 發音 | 釋義 |
|---|---|---|
| speed up 動詞 | /spiːdˈʌp/ | 加速, 加快 |
| zoom out 動詞 | /ˌzuːm ˈaʊt/ | 縮小 /縮小 |
需要注意的發音
- “sh” 和 “zh” 音: cache /kæʃ/, efficiency /ɪˈfɪʃ.ən.si/, transaction /tɹænˈzækʃən/, efficient /ɪˈfɪʃənt/, translation /tɹænzˈleɪʃən/
- 長單詞——注意重音位置: architecture /ˈɑː.kɪˌtɛk.t͡ʃə/, efficiency /ɪˈfɪʃ.ən.si/, infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, mechanism /ˈmɛk.ə.nɪ.zəm/, eliminate /ɪˈlɪm.ɪ.neɪt/
中文母語者容易讀錯的音:
- /v/ — 不要讀成 /w/,上齒輕觸下唇: server /ˈsɝvɚ/, virtual /ˈvɜɹt͡ʃuəl/, retrieve /ɹɪˈtɹiːv/, involve /ɪnˈvɑlv/, dive /daɪv/
- 詞尾子音 — 要讀清楚,後面不要加母音: cache /kæʃ/, disk /dɪsk/, database /ˈdeɪtəˌbeɪs/, fetch /fɛt͡ʃ/, technique /tɛkˈniːk/
- /r/ 和 /l/ 的區別: virtual /ˈvɜɹt͡ʃuəl/, translation /tɹænzˈleɪʃən/, crucial /ˈkɹuː.ʃəl/, translate /tɹænzˈleɪt/, prevalent /ˈpɹɛvələnt/
如何用這段影片練習
- 先完整聽一遍影片,不要開口,記下不認識的單詞。
- 用正常速度逐句跟讀,每句重複到你的節奏與說話人一致為止。
- 錄下自己的聲音並與原聲對比,特別注意 cache, server, disk 這類單詞。
什麼是跟讀法?
跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧,最初開發用於專業口譯員的培訓,並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大:您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同,跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性,語調,節奏,連讀,聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。



























