Up to JDK 22, this feature is enabled by default, which may have been reasonable when it was introduced in JDK 6 circa 2006, but from a current perspective, in the interest of making build output more robust against annotation processors being placed on the class path unintentionally, this is much less reasonable. Hence, starting with JDK 23, javac requires an additional command-line option to enable annotation processing.

Is Java heavyweight? will the container images be huge? Nope, Java is pretty good at producing decent size container images. The table below shows the container image sizes for a variety of popular open source project. Java does pretty well on these measures.

This release improves error and warning reporting for variant issues during dependency resolution. It also exposes structural details of Java compilation errors for IDE integrators, making it easier to analyze and resolve issues.

A virtual thread is not mapped 1:1 to a dedicated OS-level thread. Rather, we can think of it as a task that is scheduled to a fork-join thread pool. When a virtual thread enters a blocking call, like waiting for a Future, it relinquishes the OS thread it occupies and simply remains in memory until it is ready to resume. In the meantime, the OS thread can be reassigned to execute other VTs in the same fork-join pool

Support nullness markers on Java types to indicate that a type rejects or deliberately allows nulls. This is a preview language feature.

Leyden is not a replacement for GraalVM native images but rather a substantial evolution of the JVM, and we expect it to bring some benefits to native images as well.