https://aymenjamaaoui.dev/en/blog/Posts about development and IT: tutorials, tips, news, quizzes and a bit of retro.https://aymenjamaaoui.dev/images/og-en.pnghttps://aymenjamaaoui.dev/images/og-en.pngHugoen-USSat, 24 Oct 2026 20:45:00 +0200https://aymenjamaaoui.dev/en/blog/hexagonal-architecture-spring-boot/Sat, 24 Oct 2026 20:45:00 +0200https://aymenjamaaoui.dev/en/blog/hexagonal-architecture-spring-boot/Domain, ports and adapters in a small Spring Boot service that reads Kafka: the code, tests without Spring, and ArchUnit to keep the rule.https://aymenjamaaoui.dev/en/blog/kafka-spring-boot-locally/Sat, 24 Oct 2026 19:00:00 +0200https://aymenjamaaoui.dev/en/blog/kafka-spring-boot-locally/Kafka in KRaft mode in Docker, one Spring Boot service that publishes, another one that reads: a complete local project, with offsets and partitions.https://aymenjamaaoui.dev/en/blog/aws-locally-floci/Sat, 24 Oct 2026 05:30:00 +0200https://aymenjamaaoui.dev/en/blog/aws-locally-floci/Floci emulates AWS on your machine: what makes it different from a mock, then an example with the AWS CLI, the Java SDK (S3, DynamoDB) and the web console.https://aymenjamaaoui.dev/en/blog/java-dev-machine-mise/Sat, 24 Oct 2026 03:30:00 +0200https://aymenjamaaoui.dev/en/blog/java-dev-machine-mise/Java 8, 17 and 25, Maven, Node, Python and command-line tools: one version per project with mise, nothing as root, and a fast terminal.https://aymenjamaaoui.dev/en/blog/java-docker-kubernetes-oomkilled/Fri, 23 Oct 2026 21:30:00 +0200https://aymenjamaaoui.dev/en/blog/java-docker-kubernetes-oomkilled/Pod killed with OOMKilled (exit code 137) while the heap looks fine: what the JVM sees in a container, what adds to the heap, and how to set the memory.https://aymenjamaaoui.dev/en/blog/java-tools-jfr-jcmd-visualvm/Fri, 23 Oct 2026 09:00:00 +0200https://aymenjamaaoui.dev/en/blog/java-tools-jfr-jcmd-visualvm/GC logs, jstat, jcmd, JFR, Eclipse MAT, VisualVM: which tool for which question, what it costs in production, and a JFR example.https://aymenjamaaoui.dev/en/blog/java-heap-dump-eclipse-mat/Fri, 23 Oct 2026 02:00:00 +0200https://aymenjamaaoui.dev/en/blog/java-heap-dump-eclipse-mat/Take a heap dump with jcmd, then find the leak with Eclipse MAT: Leak Suspects, retained heap, dominator tree and the path to GC roots.https://aymenjamaaoui.dev/en/blog/java-memory-leaks/Fri, 23 Oct 2026 01:05:00 +0200https://aymenjamaaoui.dev/en/blog/java-memory-leaks/Static collection, cache, listeners, ThreadLocal, class loaders, files: six Java memory leaks reproduced, how to see them and how to fix them.https://aymenjamaaoui.dev/en/blog/read-java-gc-log/Thu, 22 Oct 2026 23:40:00 +0200https://aymenjamaaoui.dev/en/blog/read-java-gc-log/Turn on the GC log, read a G1 line word by word, follow 4 numbers and spot the warning signs: Pause Full, humongous objects, evacuation failure.https://aymenjamaaoui.dev/en/blog/java-outofmemoryerror-messages/Thu, 22 Oct 2026 22:40:00 +0200https://aymenjamaaoui.dev/en/blog/java-outofmemoryerror-messages/Java heap space, GC overhead, Metaspace, direct buffer, native thread: each OutOfMemoryError reproduced, what it means and what to check.https://aymenjamaaoui.dev/en/blog/java-garbage-collector-guide/Thu, 22 Oct 2026 16:40:00 +0200https://aymenjamaaoui.dev/en/blog/java-garbage-collector-guide/JVM memory, generations, garbage collectors, options and common myths: the essentials of the Java GC in one guide, up to date for Java 25.https://aymenjamaaoui.dev/en/blog/java-garbage-collector-myths/Thu, 22 Oct 2026 16:20:00 +0200https://aymenjamaaoui.dev/en/blog/java-garbage-collector-myths/System.gc(), finalize(), heap size, GC tuning, memory leaks: five common myths about the garbage collector, and what is true in Java 25.https://aymenjamaaoui.dev/en/blog/jvm-options-that-matter/Thu, 22 Oct 2026 15:45:00 +0200https://aymenjamaaoui.dev/en/blog/jvm-options-that-matter/-Xms, -Xmx, MaxGCPauseMillis, -Xlog, heap dump, MaxRAMPercentage: the JVM options worth knowing in Java 25, and the old ones that no longer work.https://aymenjamaaoui.dev/en/blog/java-garbage-collectors-2026/Thu, 22 Oct 2026 13:30:00 +0200https://aymenjamaaoui.dev/en/blog/java-garbage-collectors-2026/Serial, Parallel, G1, ZGC, Shenandoah, Epsilon: what each GC is for, which one the JVM picks by default and how to check it. Up to date for Java 25.https://aymenjamaaoui.dev/en/blog/gc-generations-cycles-young-old-minor-major-full/Thu, 22 Oct 2026 04:10:00 +0200https://aymenjamaaoui.dev/en/blog/gc-generations-cycles-young-old-minor-major-full/Why the JVM splits young and old objects, how an object reaches the old generation, and what minor, major and full GC really mean. Up to date for Java 25.https://aymenjamaaoui.dev/en/blog/jvm-memory-heap-stack-metaspace/Thu, 22 Oct 2026 03:40:00 +0200https://aymenjamaaoui.dev/en/blog/jvm-memory-heap-stack-metaspace/Where the JVM keeps variables, objects and classes, what lives outside the heap, and what changed after PermGen. Up to date for Java 25.https://aymenjamaaoui.dev/en/blog/one-chrome-per-google-account-macos/Thu, 22 Oct 2026 00:00:00 +0200https://aymenjamaaoui.dev/en/blog/one-chrome-per-google-account-macos/On macOS, all Chrome profiles share one icon in the Dock and Cmd+Tab. How I made one copy of Chrome per account, and what it costs.