The publishing of Java 19 in September 2022 heralded the first public release of the much-awaited Project Loom into the JVM (Java Virtual Machine) ecosystem. A brief description for those who are unaware: Project Loom is an endeavor year in the making by the developers of the Java programming language to enable the use of virtual threads within Java code. Virtual threads are named as such because, although they possess the appearance and behavior of what developers traditionally regard as threads, they are not actual OS (operating system) threads and instead are aggregated together and executed on top of such OS threads.
The primary benefit of this is that OS threads are “heavy” and bound to a relatively-small limit before their memory requirements overwhelm the operating system, whereas virtual threads are “lightweight” and can be used in much higher numbers. While the functionality of Project Loom is still in the preview phase in the Java 19 release—and “full” functionality is not forthcoming until at least the release of Java 21 in 2023 (or even further in the future)—excitement for Project Loom is quite high, and there is already movement underway in major Java ecosystems to accommodate virtual threads to their utmost potential.