JVM Internals Deep Dive 8-25 LTS

JVM Architecture Overview — runtime data areas, memory model, flag reference tableClass Loading Subsystem — delegation model, loading phases, JPMS/Jigsaw module systemExecution Engine & JIT — tiered compilation levels (0→4), inlining, escape analysis, loop vectorisation, SIMD intrinsics, speculative optimisation and deoptimisationGarbage Collection Algorithms — deep dives on G1, ZGC (coloured pointers, load barriers, concurrent relocation), and Shenandoah; full comparison table across all collectorsLTS-by-LTS Optimisation History:GC Configuration & Tuning — selection guide, essential flags, unified GC loggingMonitoring & Profiling — JFR, jcmd/jstack/async-profiler, key production metricsVirtual Threads & Modern Concurrency — VT vs platform threads, migration checklist, StructuredTaskScope patternPerformance Tuning Playbook — symptom→root cause table, AppCDS, CRaC, GraalVM NativeEvolution Timeline — Java 8→25 at a glance