How does Structured Concurrency compare to CompletableFuture for a fan-out service call?

Using CompletableFuture for a fan-out to three services typically means three separate supplyAsync() calls, an allOf() to wait for all of them, manually calling join() on each one individually, handling exceptions separately for each future, and manually canceling the others if one fails -- the result tends to be verbose, easy to get subtly wrong, and hard to read since the control flow isn't linear. Structured Concurrency handles the same scenario far more directly: try (var scope = StructuredTaskScope.open(Joiner.allSuccessfulOrThrow())) followed by three scope.fork() calls, a single scope.join(), and then reading each subtask's result with .get() -- the code reads almost like ordinary synchronous code, and sibling cancellation on failure happens automatically, with the scope itself guaranteeing every forked thread has finished by the time the try-with-resources block closes. As a rule, CompletableFuture remains the right tool when supporting Java versions before 21, or when the composition is genuinely complex and dynamic, such as a multi-stage pipeline; Structured Concurrency is the better fit on Java 21 and later for a known, fixed set of parallel tasks following a clean fan-out shape.