Jvm - GoKawiil

OpenJDK JEP 544 adds AOT native code compilation to HotSpot JVM

OpenJDK's JEP 544 proposes extending HotSpot's existing AOT cache mechanism to store precompiled native code generated during a training run, making it instantly usable when an application starts in production. If workload behavior shifts, the JVM falls back to dynamic JIT compilation to maintain performance, blending AOT and JIT approaches without requiring any code or configuration changes from developers.

openjdk.org · 2026-09-10

Investigation finds G1GC card-marking barrier makes Arrays.fill 265x slower than ParallelGC

A JMH benchmark filling two reference arrays showed drastically different results depending on garbage collector: about 0.5ms on ParallelGC versus 139ms on G1GC, despite no garbage collection occurring during the measured operations. The author traces this gap through JIT compilation and JVM flags down to a specific machine instruction responsible for the slowdown.

krzysztofslusarski.github.io · 2026-09-01

JEP 401 value classes land as preview in JDK 28, with performance caveats

JDK 28 has integrated JEP 401, a Project Valhalla milestone, as a preview feature that introduces value classes to the JVM. The author explains that these classes drop object identity, letting the JVM flatten and scalarize data in memory rather than always using pointer-based references, which can boost performance in many cases.

johan-sjolen.github.io · 2026-08-26