An ordinary programmer sharing tech and life.
Although AI coding tools let Java developers generate DTOs, interfaces, tests and business logic faster, the resulting speed boost often leaves them uneasy because the reasoning and design decisions that used to be embedded in handwritten code disappear, leading to deeper doubts during review and deployment.
The article explains that ThreadPoolExecutor’s execution flow first fills core threads, then enqueues tasks, and only creates non‑core threads after the work queue is full, so a high maximumPoolSize (e.g., 100) does not guarantee rapid thread growth, and queue choice and rejection policies critically shape scaling behavior.
The article analyzes Redis distributed locks—its three‑step verification, the limited guarantees it provides, and why small‑to‑medium projects should often prefer database constraints, idempotency keys, or state machines over adding a lock that introduces extra complexity and maintenance overhead.
Even with less than 30 QPS and normal DB CPU, a connection pool can run out in two hours because connections are held too long—often due to leaks, long‑running transactions, or async misuse—so the root cause must be traced back to the application code rather than just slow SQL.
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.
