What are the commonly used concurrency tools in Java function libraries?

The Java concurrency library provides a variety of tools, including: Thread pool: used to manage threads and improve efficiency. Lock: used to synchronize access to shared resources. Barrier: Used to wait for all threads to reach a specified point. Atomic operations: indivisible units, ensuring thread safety. Concurrent queue: A thread-safe queue that allows multiple threads to operate simultaneously.

Commonly used concurrency tools in Java function libraries

The rich concurrency libraries in Java provide a variety of tools that can help you write robust, high-performance Performance of concurrent applications. This article will introduce some of the most commonly used concurrency tools in Java function libraries and demonstrate their usage based on actual cases.

1. Thread pool

Thread pool is a mechanism for managing threads, which can improve efficiency and reduce the overhead of creating and destroying threads. The ThreadPoolExecutor class in Java allows you to configure various thread pool properties such as number of threads, maximum queue size, and denial policy.

Practical case:

// 创建一个具有 5 个线程的线程池
ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5, 5, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>());

// 提交任务到线程池
threadPool.execute(() -> System.out.println("任务 1 执行中"));
threadPool.execute(() -> System.out.println("任务 2 执行中"));

// 关闭线程池
threadPool.shutdown();

2. Lock

Lock is a synchronization mechanism that allows you to control access to shared resources. The concurrency library in Java provides various lock implementations, including:

• ReentrantLock: A reentrant lock that allows the same thread to acquire the same lock multiple times
• ReadWriteLock: A read-write lock that allows multiple threads to read shared resources at the same time, but only allows one thread to write

Practical case:

// 创建一个 ReentrantLock 对象
ReentrantLock lock = new ReentrantLock();

// 试图获取锁
if (lock.tryLock()) {
  try {
    // 对共享资源执行操作
  } finally {
    lock.unlock(); // 释放锁
  }
}

3. Barrier

A barrier is a synchronization mechanism that allows a group of threads to wait for all threads to reach a certain point. The CyclicBarrier class in Java allows you to specify the number of waiting threads and when all threads reach the barrier, they are released.

Practical case:

// 创建一个 CyclicBarrier 对象，等待 3 个线程
CyclicBarrier barrier = new CyclicBarrier(3);

// 创建线程，每个线程等待屏障释放
for (int i = 0; i < 3; i++) {
  new Thread(() -> {
    try {
      barrier.await();
      // 所有线程都到达屏障后执行操作
    } catch (BrokenBarrierException | InterruptedException e) {
      e.printStackTrace();
    }
  }).start();
}

4. Atomic operations

Atomic operations are indivisible units and cannot be interrupted by other threads. The Atomic class in Java provides a set of atomic variables and operations, such as:

• AtomicInteger: an atomic int variable
• AtomicReference: An atomic reference variable
• AtomicBoolean: An atomic Boolean variable

Actual case:

// 创建一个 AtomicInteger 对象
AtomicInteger counter = new AtomicInteger(0);

// 使用原子操作增加计数器
counter.incrementAndGet();

5. Concurrent queue

Concurrent queue is a thread-safe queue implementation that allows multiple threads to operate the queue at the same time. The concurrency library in Java provides various concurrent queues, such as:

• BlockingQueue: a blocking queue that blocks the acquisition operation when the queue is empty
• ConcurrentLinkedQueue: A non-blocking queue, implemented using a linked list

Practical case:

// 创建一个 LinkedBlockingQueue 对象
BlockingQueue<Integer> queue = new LinkedBlockingQueue<>();

// 向队列添加元素
queue.offer(1);
queue.offer(2);

// 从队列获取元素
Integer element = queue.poll();

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