Lightweight threads in Java 21.

Overview

Lightweight threads in Java 21.

Example 

  try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
    executor.submit(() -> System.out.println("Virtual thread"));
}

Common Use Cases

  • High-throughput server applications
  • Parallel data processing

Pitfalls to Avoid

  • Pinning virtual threads with synchronized blocks on JDK 21
  • Unbounded thread creation
  • ExecutorService
  • CompletableFuture

Best Practices

  • Understand when to use virtual threads versus simpler alternatives
  • Write unit tests covering edge cases and failure paths
  • Follow Java conventions and prefer standard library APIs when available
  • Profile before optimizing — measure impact in your specific workload