Java Guru

Learn Java, Spring Boot, Database, System Design, Performance, and Clean Code through concise, easy-to-understand articles grounded in real-world experience.

Featured

• Java Interview Prep #1: Java Core (JVM, GC, Concurrency) — Junior to Senior

  Published: 10 Aug, 2026 |  at  10:00 AM

  The spine of every Java interview — JVM memory, garbage collection, the JMM, and concurrency. Junior recites; senior proves they've debugged a production OutOfMemoryError.

• Kafka: Lessons Only Production Can Teach You

  Published: 24 Jan, 2026 |  at  07:31 AM

  No Kafka tutorial prepares you for the 2 AM wake-up call when consumer lag spirals out of control. Hard-earned lessons about Kafka in production.

• High-Load System Design: Comprehensive Solutions from Front-end to Back-end

  Published: 21 Sep, 2025 |  at  04:32 AM

  A comprehensive guide to high-load system design: from frontend optimization, caching, query optimization, backend patterns, request management, to monitoring and autoscaling.

• Saga Pattern: When Theory Meets Reality

  Published: 2 Sep, 2025 |  at  09:02 AM

  Real-world lessons from implementing Saga Pattern: partial failure, imperfect compensation, duplicate events, and the trade-off between Orchestration and Choreography.

• Hundreds of Orders Vanished in Just 3 Minutes – All Because of One Forgotten Config Line

  Published: 18 Jun, 2025 |  at  03:13 PM

  A real case study on the consequences of forgetting graceful shutdown configuration in Spring Boot: lost orders, Kafka messages, and lessons learned.

• I Don't Like Microservices, and Here's Why

  Published: 1 Jun, 2025 |  at  01:52 PM

  A real-world perspective from a backend developer: when to and when not to use microservices, trade-offs with monoliths, and lessons for small teams.

Recent Posts

• OOP, SOLID & Design Patterns: Engineering Judgment for Real Java Code

  Published: 11 Aug, 2026 |  at  10:00 AM

  A problem-first guide to OOP, SOLID and Design Patterns in Java. Learn how to recognize design pressure in real code, refactor toward better structure, and — just as importantly — know exactly when NOT to apply a principle or pattern.

• Java Interview Prep #8: Senior Mindset & Behavioral — Junior to Senior

  Published: 10 Aug, 2026 |  at  10:35 AM

  Senior interviews test judgment and communication as much as code. How to present trade-offs, admit uncertainty, and tell stories that prove senior-level ownership.

• Java Interview Prep #3: Spring Boot — Junior to Senior

  Published: 10 Aug, 2026 |  at  10:30 AM

  Spring Boot is where Java backend seniors live. IoC/DI, the bean lifecycle, transaction management, and the auto-configuration magic interviewers expect you to see through.

• Java Interview Prep #7: System Design — Junior to Senior

  Published: 10 Aug, 2026 |  at  10:25 AM

  System design is the senior capstone — a 45-minute judgment test. Process, capacity estimation, caching, CAP, scalability, and observability.