Note: JEP 505 is a preview feature in Java 25 (5th preview). Enable with --enable-preview. The API has been stable for several rounds and is expected to finalize in Java 26. The Problem with Unstructured Concurrency Classic Java concurrency with ExecutorService is unstructured: you submit tasks, and those tasks have no formal relationship with the code that submitted them. This causes three recurring problems: Problem 1: Partial failure leaves orphaned tasks ExecutorService exec = Executors.