Java 21’s Best Kept Secrets: Hidden Gems for Performance & Productivity

Java 21 brings a wealth of improvements, but some enhancements remain relatively under-the-radar. This post dives into some hidden gems that can significantly boost your performance and productivity.

Enhanced Performance with Structured Concurrency

Java 21 refines structured concurrency, a feature introduced in previous releases. This isn’t just a minor tweak; it leads to substantial improvements in managing concurrent tasks, particularly in error handling and resource management.

Easier Error Handling

Before structured concurrency, handling exceptions in a thread pool could be complex. Now, exceptions thrown within structured blocks are automatically propagated to the parent scope, simplifying exception handling and preventing resource leaks.

StructuredTaskScope scope = new StructuredTaskScope();

task1 = scope.fork(() -> {
    //Some potentially error prone code...
    throw new RuntimeException("Task 1 Failed");
});

task2 = scope.fork(() -> {
    //Some other code...
});

try {
    scope.join();
} catch (InterruptedException e) {
    //Handle interruption
} catch (StructuredTaskScope.UncaughtException e) {
    //Handle exceptions from tasks
    System.err.println("Task failed: " + e.getCause().getMessage());
}

Improved Resource Management

Structured concurrency also ensures resources are released even if tasks fail. This prevents resource exhaustion and improves the overall stability of your application.

Enhanced Productivity with Improved Virtual Threads

Virtual threads (Project Loom) continue to mature in Java 21, providing even better performance and ease of use for concurrent programming.

Lighter Weight

Virtual threads are significantly lighter weight than traditional platform threads, allowing you to handle a far larger number of concurrent tasks with reduced resource consumption.

Simplified Concurrency

Writing concurrent code becomes simpler with virtual threads. You can write code that looks synchronous, but behaves concurrently, enhancing readability and maintainability.

ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

List<Future<String>> futures = new ArrayList<>();
for (int i = 0; i < 1000; i++) {
    futures.add(executor.submit(() -> "Task " + i));
}

for (Future<String> future : futures) {
    System.out.println(future.get());
}

Other Hidden Gems:

• Improved foreign function and memory API: More robust and feature-rich, easing interaction with native code.
• Vector API enhancements: Continued improvements provide better performance for vectorized computations.
• Updates to the garbage collector: Further refinements improve garbage collection efficiency and reduce pauses.

Conclusion

Java 21 offers more than just headline features. By understanding and leveraging the subtle enhancements in structured concurrency, virtual threads, and other areas, developers can significantly improve their application’s performance and their own productivity. These ‘hidden gems’ are key to building more robust, efficient, and maintainable Java applications.