GC Changes Across Java 9–11 Release Change JEP Java 9 G1GC becomes the default GC JEP 248 Java 9 Unified GC logging (-Xlog:gc*) JEP 271 Java 10 Parallel Full GC for G1 JEP 307 Java 10 Application Class-Data Sharing (AppCDS) JEP 310 Java 11 Epsilon: No-Op GC JEP 318 Java 11 ZGC: Scalable Low-Latency GC (experimental) JEP 333 G1GC as Default (JEP 248, Java 9) G1 (Garbage-First) replaced Parallel GC as the default on systems with ≥2 CPUs and ≥2 GB heap.

Production Readiness Checklist [ ] JDK distribution chosen and version pinned [ ] Heap and Metaspace sized correctly [ ] GC selected and tuned for your workload [ ] Container-aware JVM flags set [ ] AppCDS archive built for faster startup [ ] JFR always-on recording configured [ ] GC logging enabled with rotation [ ] Security-related algorithms locked down [ ] Thread and connection pool sizes verified [ ] JVM exit flags prevent silent crashes Baseline JVM Flags for Java 11 Start with these flags and tune from here: