What tools or libraries for multithreading have you used in your projects?

In Java, the following tools and libraries are often used for multithreading:

• java.lang.Thread — the basic class for creating and managing threads.
• java.util.concurrent — a package with high-level abstractions:
  • ExecutorService for managing thread pools.
  • Future and Callable for asynchronous tasks with results.
  • CountDownLatch, Semaphore, CyclicBarrier for synchronization.
  • ConcurrentHashMap, BlockingQueue for thread-safe collections.
• ForkJoinPool — for implementing parallel algorithms with task splitting.
• CompletableFuture — for conveniently building chains of asynchronous operations.

Example of using ExecutorService:

ExecutorService executor = Executors.newFixedThreadPool(4);
Future<Integer> future = executor.submit(() -> {
    // Some computational task
    return 42;
});

Integer result = future.get();
executor.shutdown();