High CPU, GC spikes, or slow startup are common production issues, but logs and metrics don’t always reveal what the JVM is actually doing. Java Flight Recorder (JFR) provides a precise, low-overhead view of JVM behavior, safe for use even in production environments. In this video, you’ll learn how to use JFR to identify real bottlenecks such as CPU hotspots, memory allocation pressure, thread contention, and I/O stalls. We walk through the full workflow, including starting recordings with JVM flags, controlling them via jcmd, running JFR inside Docker containers, and attaching to live systems using ephemeral containers. Then we analyze a real Spring Boot recording in JDK Mission Control, breaking down GC behavior, allocation patterns, thread states, and method-level hotspots. If you want to move from symptoms to root cause with more confidence, this approach will help. Full article with commands and examples: [https://bell-sw.com/blog/how-to-profile-java-applications-with-jfr-beginner-s-guide/](https://bell-sw.com/blog/how-to-profile-java-applications-with-jfr-beginner-s-guide/)
If your repository layer has multiple queries for different filter combinations, your data access logic is already getting harder to maintain. In this video, we implement dynamic SQL queries in Spring Data JPA using Specifications — a composable approach that helps avoid query duplication and keeps your filtering logic clean. We build a flexible filtering system with optional parameters (category, language, format, price) and show how Specification.unrestricted() skips empty filters, while Specification.allOf(...) combines them into a single query. We also address a common issue: string-based field access. It’s fragile and can break at runtime when your model changes. Using the JPA Static Metamodel, we move to compile-time safety. The result is a cleaner, more maintainable way to implement dynamic filtering in Spring-based applications.
A comparison of major OpenJDK distributions (Temurin, Liberica, Zulu, Corretto, Semeru, etc.), covering who maintains them, how updates are delivered, and what lifecycle guarantees they provide. We also explain why upstream OpenJDK isn’t production-ready and how your vendor choice impacts real-world systems. Useful for Spring Boot, containers, and Kubernetes to avoid hidden risks and choose the right runtime.


