Proposed Java API would enable sharing of immutable data across threads

Java could obtain a capability for sharing immutable info throughout threads, dependent on a plan now under thought in the OpenJDK realm.

An OpenJDK proposal for extent-regional variables, presently an incubating API, would deliver a programming model to share knowledge the two within just a thread and with youngster threads. Extent-local variables are favored to thread-local variables, specifically when utilizing significant figures of digital threads, the proposal states.

The proposal lists four aims driving the incubating API:

• Simplicity of use, to simplify reasoning about information stream.
• Comprehensibility, to make the life time of shared info seen from the syntactic structure of code.
• Robustness, to assure that details shared by a caller can be retrieved only by authentic callees.
• Functionality, to address shared data as immutable to permit sharing by a big quantity of threads and permit runtime optimizations.

The extent neighborhood-variables API at present is not slated for any particular edition of common Java. The earliest it could perhaps surface would be in Java 20, due in March 2023. Java 19, or Java Enhancement Package 19, thanks to arrive on September 20, is closed to new capabilities.

The extent-community variables approach does not involve transforming the Java programming language alone. There also is no intent to need migration absent from thread-nearby variables, or to deprecate the present ThreadLocal API.