An ordinary programmer sharing tech and life.
The article explains why MySQL's InnoDB engine uses REPEATABLE READ by default, clarifies the differences between snapshot and current reads, compares RC and RR isolation levels, details MVCC mechanics, and provides a concise interview answer template with practical SQL examples.
On July 9, OpenAI released GPT‑5.6, introducing three tiered models—Sol, Terra, and Luna—with distinct pricing and performance, merging the standalone Codex app into ChatGPT, adding an ultra‑mode for multi‑agent collaboration, enhanced design capabilities, and showing benchmark gains over competitors.
The article explains what Lombok’s @Data annotation expands to, warns that its default @EqualsAndHashCode callSuper is false causing equals/hashCode to ignore superclass fields, discusses the need to manually declare serialVersionUID for Serializable classes, and recommends using @Getter/@Setter with explicit @EqualsAndHashCode when inheritance is involved.
The article explains that idempotency prevents the same operation from being executed twice, illustrates a real double‑charge bug, evaluates five concrete approaches—including Redis check‑then‑set, DB unique index, optimistic lock, Redis distributed lock, and a message deduplication table—details their failure conditions and suitable scenarios, and recommends combining Redis lock with a database unique index for the most robust protection.
A midnight payment outage caused a user to be charged three times because a Lombok‑generated @Data class ignored the superclass requestId in its equals method, breaking idempotency checks; the article explains the root cause, reproduces the bug, and offers concrete guidelines for safe Lombok usage.
At 3 am a production server saw Full GC spike from once a day to ten times a minute because a ThreadLocal holding a large object was never removed, leading to a memory leak that almost took the machine down, and the article explains the root cause, internal mechanics, and remediation strategies.
The article explains how HashMap can enter an infinite loop, lose data, or corrupt entries when accessed concurrently, illustrates the root causes with JDK 1.7 and 1.8 source code, compares alternative thread‑safe maps, and shows how to answer this classic interview question.
The article reviews the end‑to‑end online lending process involving platforms, operators, fund providers, local banks and the central bank, discusses the technical hurdles of maintaining a legacy JSP system with closed‑source components, and reflects on the strategic importance of the platform ecosystem.
This article explains Retrieval‑Augmented Generation (RAG), describing its definition, why it complements large language models, the end‑to‑end workflow, its four core components—embedding, vector database, retriever, generator—and the value it adds by providing up‑to‑date knowledge and reducing model hallucinations.
The article reviews Andrew Ng’s ‘AI for Everyone’ course, explaining AI bias with a facial‑recognition example and mitigation tips, describing adversarial attacks and defenses, outlining harmful AI uses such as deepfakes and privacy threats, and discussing McKinsey’s job‑displacement and creation forecasts alongside AI‑assisted programming tools.
