JDK 19: Java 19 begins to take shape

Java Development Kit 19, expected to arrive this September, now has an initial feature officially proposed to target it: A port of the JDK to the open source Linux/RISC-V instruction set architecture (ISA).

JDK 19, or simply Java 19, potentially could host a vast number of features, ranging from universal generics to value objects, according to plans under way for enhancing Java. But so far, the RISC-V port is the only officially proposed feature to target JDK 19. JDK 19 would follow JDK 18, which is due March 22. Standard Java is on a six-month release cadence.

With the Linux/RISC-V port, Java would gain support for a hardware instruction set that is already supported by a wide range of language toolchains. RISC-V actually is a family of related ISAs. The Linux/RISC-V port would only support the RV64GV configuration of RISC-V, a general purpose 64-bit ISA that includes vector instructions. The developers of Java may consider other RISC-V configurations in the future.

The port would supporting the following HotSpot VM options: the template interpreter, C1 (client) JIT compiler, C2 (server) JIT compiler, and all current mainline garbage collectors including ZGC and Shenandoah. The actual porting is nearly complete; the focus of the JDK Enhancement Proposal (JEP) is integration of the port into the JDK mainline repository.

Aside from the RISC-V port, a preview of a foreign function and memory API, allowing Java programs to interoperate with code and data outside of the JVM runtime, also seems destined to being officially targeted to JDK 19, since the API proposal itself cites JDK 19 as a destination. But as of March 14, the foreign function and memory API was not listed among the features on the OpenJDK’s JDK 19 page.

Both JDK 18 and JDK 19 are due to be short-term releases, with only six months of top-level, Premier support. The current release, JDK 17, is a Long Term Support (LTS) release, with several years of support.