Focused on Java interview questions and practical article sharing, covering algorithms, databases, Spring Boot, microservices, high concurrency, JVM, Docker containers, and ELK-related knowledge. Looking forward to progressing together with you.
The article analyzes common pitfalls of Spring Event—such as publishing during shutdown or early startup, unsuitability for strong‑consistency use cases, and the need for graceful shutdown, idempotent listeners, and extra reliability measures—while comparing it with message‑queue solutions.
The article explains warmup (prewarm) as the practice of moving a Java system from a cold to a hot state before traffic arrives, covering JVM JIT compilation, cache preloading, connection‑pool and thread‑pool initialization, service gray‑release, and how these steps prevent cold‑start failures in high‑concurrency scenarios.
This article provides a practical overview of four popular intranet penetration tools—nps, frp, ew, and ngrok—detailing their core concepts, key features, and step‑by‑step usage instructions with configuration examples and command‑line snippets.
The article defines circuit breaker as a self‑protective mechanism that prevents cascade failures in distributed systems, explains the avalanche effect, details the three‑state state machine, compares Hystrix, Sentinel and Resilience4j, provides a Sentinel code example, and lists common interview questions and answers.
This article explains why the common getRemoteAddr() call often returns proxy addresses, details the underlying IP header propagation, and provides a production‑grade utility class, Spring Boot configuration, advanced interception, testing, and best‑practice guidelines for reliably obtaining the true client IP.
The article explains what JWT is, why its stateless design can cause problems, compares pure JWT, JWT with a blacklist, and storing tokens in Redis (whitelist), and provides a step‑by‑step guide on how to discuss these options convincingly in a Java interview.
The article analyses why XXL‑Job’s separate registration, configuration, and weak sharding cause state inconsistency, observability gaps, and duplicate processing, then proposes JobFlow – a lightweight scheduler that removes redundant components, adds full‑traceId tracing, true sharding with distributed locks, exponential retry, and cloud‑native configuration managed by Nacos, all illustrated with concrete code snippets and deployment diagrams.
The article explains why sharding a table requires a global unique ID, outlines six major ID generation strategies, compares their performance, ordering, dependencies and suitable scenarios, and provides practical guidance for choosing the right solution in production environments.
The article explains how the forceful kill -9 command can corrupt data and break transactions in Java services, demonstrates the risks with MyISAM and distributed systems, and provides step‑by‑step guides for graceful shutdown using kill -15, ConfigurableApplicationContext.close, Spring Boot Actuator, and @PreDestroy hooks.
When a Spring Boot project is packaged as a jar it runs with the embedded Tomcat using the application's own configuration, while a war package relies on an external Tomcat container, adopts the container's settings such as the default 8080 port, and requires additional Maven configuration and a ServletInitializer class.
