Home >> Linux >> Java’s Enhancement Proposals Pursue Virtual Threads, Data Aggregate Types, and Better Communication with C Libraries

Java’s Enhancement Proposals Pursue Virtual Threads, Data Aggregate Types, and Better Communication with C Libraries

Oracle’s Java magazine takes a look at some current JDK Enhancement Proposals, “the vehicle of long standing for updating the Java language and the JVM.”

Today, concurrency in Java is delivered via nonlightweight threads, which are, for all intents, wrappers around operating-system threads… Project Loom aims to deliver a lighter version of threads, called virtual threads. In the planned implementation, a virtual thread is programmed just as a thread normally would be, but you specify at thread creation that it’s virtual. A virtual thread is multiplexed with other virtual threads by the JVM onto operating system threads. This is similar in concept to Java’s green threads in its early releases and to fibers in other languages… Because the JVM has knowledge of what your task is doing, it can optimize the scheduling. It will move your virtual thread (that is, the task) off the OS thread when it’s idle or waiting and intelligently move some other virtual thread onto the OS thread. When implemented correctly, this allows many lightweight threads to share a single OS thread. The benefit is that the JVM, rather than the OS, schedules your task. This difference enables application-aware magic to occur behind the curtains…

Project Valhalla aims to improve performance as it relates to access to data items… by introducing value types, which are a new form of data type that is programmed like objects but accessed like primitives. Specifically, value types are data aggregates that contain only data (no state) and are not mutable. By this means, [value types] can be stored as a single array with only a single header field for the entire array and direct access to the individual fields…

Project Panama simplifies the process of connecting Java programs to non-Java components. In particular, Panama aims to enable straightforward communication between Java applications and C-based libraries…
Several Amber subprojects are still in progress.

Sealed classes, which have been previewed in the last few Java releases and are scheduled to be finalized in Java 17. Sealed classes (and interfaces) can limit which other classes or interfaces can extend or implement them…
Pattern matching in switches is a feature that will be previewed in Java 17…

The article concludes that Java’s past and current projects “testify to how much Java has evolved and how actively the language and runtime continue to evolve.”


Read more of this story at Slashdot.

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