Lesson 6: 悲觀與樂觀：資料庫鎖 (Locking) 機制與並發處理
Dec 7, 2025 · 4 min read · 在上一篇文說到了：三種讀取異常，也介紹了四種隔離等級，如果是第一次接觸到這些概念的人一定會有疑問： Q：既然 RR 已經保證『可重複讀』了，為什麼搶票系統還是會超賣？資料庫不是隔離了嗎？ A：隔離級別（透過 MVCC）通常只保證「你看得到的資料」是一致的（快照），但它擋不住多個人同時對同一筆資料進行「寫入」 回到搶票案例： A 讀取 (Select)：MVCC 給了 A 一張「剩餘 1 張」的照片。 B 讀取 (Select)：MVCC 給了 B 一張「剩餘 1 張」的照片。 A 寫入 (...
Join discussionHandling concurrency in Java
Nov 24, 2025 · 5 min read · Concurrency is about multiple threads executing at the same time. Without proper handling, threads can interfere with each other, causing race conditions and data corruption. What's a race condition? When two threads try to read and modify the same d...
Join discussionConcurrency Testing: Detecting Race Conditions
Nov 16, 2025 · 5 min read · Concurrency testing (also known as concurrent testing) is a technique used to detect possible defects while multiple users or concurrent users in performance testing scenarios access an application simultaneously. In software quality assurance and co...
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How One Extra Second Broke Half the Internet: The 2012 Leap Second Disaster
Nov 3, 2025 · 7 min read · A deep dive into one of computing's most fascinating timing bugs What's a Leap Second? Before we dive into the chaos, let's understand what caused it: Earth's rotation is slightly irregular - Earthquakes, tides, and other geological phenomena affec...
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Can Machine Learning Predict Deadlocks? Uncovering the Silent Killers in Software
Oct 20, 2025 · 7 min read · Introduction: Ever had your app freeze out of nowhere, and you're just left sitting in front of the screen wondering what happened? Then chances are, you've encountered a deadlock—one of the sneakiest and most infuriating bugs in concurrent programmi...
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Níveis de Isolamento no SQL Server: guia prático com exemplos
Aug 27, 2025 · 4 min read · Introdução Concorrência é a arte de manter integridade dos dados enquanto várias transações acontecem ao mesmo tempo. O isolamento determina como leituras e escritas interagem — e, por consequência, o que bloqueia o quê, quando surgem leituras sujas,...
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Transações no SQL Server: do básico ao XACT_ABORT, TRY…CATCH e níveis de isolamento
Aug 19, 2025 · 6 min read · Introdução Transações são a base da integridade em bancos de dados. Quando bem definidas, garantem as propriedades ACID: Atomicidade, Consistência, Isolamento e Durabilidade. Neste guia prático você verá, na prática, os tipos de transação no SQL Serv...
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Deadlocks and Auto-commit/Transection in Apache NiFi
Jul 23, 2025 · 4 min read · What Is a Deadlock? A deadlock is a situation where two or more transactions are each waiting for the other to release a resource, such as a database lock. As a result, none of the transactions can proceed, and the system halts execution for those se...
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Process synchronization - An easy explanation
Jul 20, 2025 · 2 min read · Process Synchronization is simply about running multiple processes that are accessing the same common resource (or resources) in a specific, controlled order so that everything goes smoothly and there’s no conflict. Here, multiple processes (or even ...
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