JDK 27 has entered Rampdown Phase 2, with general availability scheduled for September 15. The headline change is JEP 523: G1 is now the default garbage collector in all environments, replacing the previous behavior where Serial GC was chosen in constrained environments (single CPU or less than 1792 MB RAM). G1 now offers comparable native memory overhead and lower latency than Serial in those settings. Other JEPs integrated include post-quantum hybrid key exchange for TLS 1.3 (JEP 527), Compact Object Headers by Default (JEP 534), Structured Concurrency 7th Preview (JEP 533), and more. JDK 28 early-access builds are also available, featuring a new jlink keystore plugin for customizing CA certificates in runtime images. Applications running in constrained environments without an explicit GC flag should benchmark with different collectors to find the best fit.
