Java多线程并发编程

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public class ThreadTest {
  public static void main(String[] args) {
    Thread thread = new ThreadDemo();
    thread.start();
  }
}

class ThreadDemo extends Thread {
  @Override
  public void run() {
    System.out.println("do something");
  }
}

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public class ThreadTest {
  public static void main(String[] args) {
    Thread thread = new Thread(new RunnableDemo());
    thread.start();
  }
}

class RunnableDemo implements Runnable {
  @Override
  public void run() {
    System.out.println("do something");
  }
}

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public class ThreadTest {
  public static void main(String[] args) throws Exception {
    FutureTask<String> futureTask = new FutureTask<>(new CallableDemo());
    Thread thread = new Thread(futureTask);
    thread.start();     //此时Callable接口已经被调用
    String result = futureTask.get();
    System.out.println(result);
  }
}

class CallableDemo implements Callable<String> {
  @Override
  public String call() throws Exception {
    return "do something";
  }
}

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public class ThreadTest {
  public static void main(String[] args) {
    Timer timer = new Timer();
    timer.schedule(new TimerTaskDemo(),1000);
  }
}

class TimerTaskDemo extends TimerTask {
  @Override
  public void run() {
    System.out.println("do something");
  }
}

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public class ThreadTest {
  public static void main(String[] args) {
    ExecutorService executor = Executors.newFixedThreadPool(5);
    executor.execute(new ExecutorDemo());
    executor.shutdown();	//线程池销毁，正在执行和在队列等待的线程不会销毁
  }
}

class ExecutorDemo implements Runnable {
  @Override
  public void run() {
    System.out.println("do something");
  }
}

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public class DeadLockTest {

  public static final Object resource1 = new Object();
  public static final Object resource2 = new Object();

  public static void main(String[] args) {

    new Thread(() -> {
      synchronized (resource1) {
        try {
          Thread.sleep(500);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() + "：等待");
        synchronized (resource2) {
          System.out.println(Thread.currentThread().getName() + "：可以执行");
        }
      }
    }, "A").start();

    new Thread(() -> {
      synchronized (resource2) {
        try {
          Thread.sleep(500);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() + "：等待");
        synchronized (resource1) {
          System.out.println(Thread.currentThread().getName() + "：可以执行");
        }
      }
    }, "B").start();
  }

}

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public class LiveLock {
  static volatile int count = 10;

  // 无法解锁，一个想加到20，一个想减到0
  public static void main(String[] args) {
    Thread t1 = new Thread(() -> {
      // 期望减到 0 退出循环
      while (count > 0) {
        try {
          TimeUnit.MILLISECONDS.sleep(500);
        } catch (InterruptedException e) {
          throw new RuntimeException(e);
        }

        count--;
        System.out.println("t1 count: " + count);
      }
    }, "t1");
    Thread t2 = new Thread(() -> {
      // 期望超过 20 退出循环
      while (count < 20) {
        try {
          TimeUnit.MILLISECONDS.sleep(500);
        } catch (InterruptedException e) {
          throw new RuntimeException(e);
        }

        count++;
        System.out.println("t2 count: " + count);
      }
    }, "t2");

    t1.start();
    t2.start();

    try {
      t1.join();
      t2.join();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    System.out.println("main end");
  }
}

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public class ThreadStarvingTest {

  public static void main(String[] args) {
    ExecutorService executorService = Executors.newFixedThreadPool(2);

    executorService.submit(() -> {
      System.out.println(currentThreadName() + "接待客人");
      Future<String> cook = executorService.submit(() -> {
        System.out.println(currentThreadName() + "做回锅肉");
        return "回锅肉";
      });

      try {
        System.out.println(currentThreadName() + "上" + cook.get()); 
      } catch (InterruptedException e) {
        e.printStackTrace();
      } catch (ExecutionException e) {
        e.printStackTrace();
      }
    });

    executorService.submit(() -> {
      System.out.println(currentThreadName() + "接待客人");
      Future<String> cook = executorService.submit(() -> {
        System.out.println(currentThreadName() + "做鱼香肉丝");
        return "鱼香肉丝";
      });

      try {
        System.out.println(currentThreadName() + "上" + cook.get());
      } catch (InterruptedException e) {
        e.printStackTrace();
      } catch (ExecutionException e) {
        e.printStackTrace();
      }
    });

  }

  public static String currentThreadName() {
    return Thread.currentThread().getName();
  }

}

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public class NotifyTest {

  public static void main(String[] args) throws InterruptedException {
    NotifyRunnable notifyRunnable = new NotifyRunnable();
    new Thread(notifyRunnable).start();
    TimeUnit.SECONDS.sleep(5);
    notifyRunnable.setFlag(false);
    synchronized (notifyRunnable) {
      notifyRunnable.notify();
    }
  }
}

class NotifyRunnable implements Runnable {
  private volatile boolean flag = true;

  public void setFlag(boolean flag) {
    this.flag = flag;
  }

  public synchronized void deal() {
    try {
      // synchronized的是当期对象，这里需要while循环，被唤醒之后是继续执行的
      while(flag) {
        wait();
      }
      System.out.println("唤醒了一个线程");
    } catch ( InterruptedException e) {
      e.printStackTrace();
    }
  }

  @Override
  public void run() {
    deal();
  }
}

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public class Paker {

  public static void main(String[] args) {
    Thread t1  = new Thread(() -> {
      System.out.println("start...");

      try {
        TimeUnit.SECONDS.sleep(1);
      } catch (InterruptedException e) {
        throw new RuntimeException(e);
      }

      System.out.println("park...");
      LockSupport.park();
      System.out.println("resume...");
    });

    t1.start();
    try {
      TimeUnit.SECONDS.sleep(3);
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    LockSupport.unpark(t1);
  }
}

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public class InterruptTest {

  public static void main(String[] args) throws InterruptedException {
    Thread t1 = new Thread(()->{
      try {
        TimeUnit.SECONDS.sleep(3);
      } catch (InterruptedException e) {
        throw new RuntimeException(e);
      }
    }, "t1");
    t1.start();
    TimeUnit.SECONDS.sleep(1);
    t1.interrupt();
    // 打印false
    System.out.println(" 打断状态: " + t1.isInterrupted());
  }
}

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public class InterruptTest {

  public static void main(String[] args) throws InterruptedException {
    Thread t1 = new Thread(()->{
      while(true) {
        Thread current = Thread.currentThread();
        boolean interrupted = current.isInterrupted();
        if(interrupted) {
          System.out.println(" 打断状态: " + interrupted);
          break;
        }
      }
    }, "t2");
    t1.start();
    TimeUnit.SECONDS.sleep(1);
    t1.interrupt();
  }
}

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public class InterruptTest {

  public static void main(String[] args) throws InterruptedException {
    Thread t1 = new Thread(() -> {
      System.out.println("park...");
      LockSupport.park();
      System.out.println("unpark...");
      // 打印 true
      System.out.println("打断状态： " + Thread.currentThread().isInterrupted());
    }, "t1");
    t1.start();
    TimeUnit.SECONDS.sleep(1);
    t1.interrupt();
  }

}

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public class JoinDemo {

  public static void main(String[] args) {
    Thread t1 = new Thread(() -> {
      try {
        TimeUnit.SECONDS.sleep(3);
      } catch (InterruptedException e) {
        System.out.println(e);
      }
    });
    t1.start();

    try {
      t1.join();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    // 3s 之后才会打印，即t1执行完成打印
    System.out.println("main end");
  }
}

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public final void join() throws InterruptedException {
  join(0);
}

public final synchronized void join(long millis) throws InterruptedException {
  long base = System.currentTimeMillis();
  long now = 0;

  if (millis < 0) {
    throw new IllegalArgumentException("timeout value is negative");
  }

  if (millis == 0) {
    // 如果线程存活一直调用wait（即使被打断也会继续阻塞）
    while (isAlive()) {
      wait(0);
    }
  } else {
    // 有时间的等待，考虑了打断的影响
    while (isAlive()) {
      long delay = millis - now;
      if (delay <= 0) {
        break;
      }
      wait(delay);
      now = System.currentTimeMillis() - base;
    }
  }
}

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public interface Lock {

  // 获取锁。如果锁不可用，将禁用当前线程，并且在获得锁之前，该线程将一直处于休眠状态
  void lock();

  // 获取锁，等待过程中如果当前线程被中断，则抛出异常，此时加锁还未成功不需要释放资源
  void lockInterruptibly() throws InterruptedException;

  // 仅在调用时锁为空闲状态才获取该锁。如果锁可用立即返回值true。如果锁不可用，立即返回值 false
  boolean tryLock();

  // 如果锁在给定的等待时间内空闲，并且当前线程未被中断，则获取锁，如果等待期间被中断，则抛出异常
  boolean tryLock(long time, TimeUnit unit) throws InterruptedException;

  // 释放锁。锁必须由当前线程持有。调用Condition.await()将在等待前以原子方式释放锁
  void unlock();

  // 返回绑定到此Lock实例的新Condition实例
  Condition newCondition();
}

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//头节点
private transient volatile Node head;

//尾节点
private transient volatile Node tail;

//共享变量，使用volatile修饰保证线程可见性，用于记录了加锁次数
private volatile int state;

// 队列头节点，头结点不储存数据
private transient volatile Node head;

// 队列尾节点
private transient volatile Node tail;

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static final class Node {
  /** 节点为共享模式下等待 */
  static final Node SHARED = new Node();

  /** 节点为独占模式下等待 */
  static final Node EXCLUSIVE = null;

  /** 当前节点由于超时或中断被取消 */
  static final int CANCELLED =  1;

  /** 表示当前节点的前节点被阻塞 */
  static final int SIGNAL    = -1;

  /** 当前节点在等待condition */
  static final int CONDITION = -2;

  /** 状态需要向后传播 */
  static final int PROPAGATE = -3;

  volatile int waitStatus;

  volatile Node prev;

  volatile Node next;

  volatile Thread thread;

  Node nextWaiter;
}

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//独占模式下获取资源
public final void acquire(int arg) {
  if (!tryAcquire(arg) && acquireQueued(addWaiter(Node.EXCLUSIVE), arg))
    selfInterrupt();
}

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private Node addWaiter(Node mode) {
  Node node = new Node(Thread.currentThread(), mode);
  Node pred = tail;
  //尝试快速入队
  if (pred != null) { //队列已经初始化
    node.prev = pred;
    if (compareAndSetTail(pred, node)) {
      pred.next = node;
      return node; //快速入队成功后，就直接返回了
    }
  }
  //快速入队失败，也就是说队列都还每初始化
  enq(node);
  return node;
}

//执行入队
private Node enq(final Node node) {
  for (;;) {
    Node t = tail;
    // 如果没有队尾即还没初始化
    if (t == null) { 
      //如果队列为空，用一个空节点充当队列头
      if (compareAndSetHead(new Node()))
        //尾部指针也指向队列头
        tail = head;
    } else {
      //队列已经初始化，入队
      node.prev = t;
      if (compareAndSetTail(t, node)) {
        t.next = node;
        //打断循环
        return t;
      }
    }
  }
}

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final boolean acquireQueued(final Node node, int arg) {
  boolean failed = true;
  try {
    boolean interrupted = false;
    for (;;) {
      //拿到node的上一个节点
      final Node p = node.predecessor();
      //前置节点为head，说明可以尝试获取资源。排队成功后，尝试拿锁
      if (p == head && tryAcquire(arg)) {
        //获取成功，更新head节点
        setHead(node);
        p.next = null; // help GC
        failed = false;
        return interrupted;
      }
      //尝试拿锁失败后，根据条件进行park
      if (shouldParkAfterFailedAcquire(p, node) && parkAndCheckInterrupt())
        interrupted = true;
    }
  } finally {
    if (failed)
      cancelAcquire(node);
  }
}
//获取资源失败后，检测并更新等待状态
private static boolean shouldParkAfterFailedAcquire(Node pred, Node node) {
  int ws = pred.waitStatus;
  if (ws == Node.SIGNAL)
    return true;
  if (ws > 0) {
    do {
      //如果前节点取消了，那就往前找到一个等待状态的接替你，并排在它的后面
      node.prev = pred = pred.prev;
    } while (pred.waitStatus > 0);
    pred.next = node;
  } else {
    compareAndSetWaitStatus(pred, ws, Node.SIGNAL);
  }
  return false;
}
//阻塞当前线程，返回中断状态
private final boolean parkAndCheckInterrupt() {
  LockSupport.park(this);
  return Thread.interrupted();
}

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// 公平锁的实现
protected final boolean tryAcquire(int acquires) {
  final Thread current = Thread.currentThread();
  int c = getState();
  if (c == 0) {
    if (!hasQueuedPredecessors() &&
        compareAndSetState(0, acquires)) {
      setExclusiveOwnerThread(current);
      return true;
    }
  }
  else if (current == getExclusiveOwnerThread()) {
    int nextc = c + acquires;
    if (nextc < 0)
      throw new Error("Maximum lock count exceeded");
    setState(nextc);
    return true;
  }
  return false;
}

// 非公平锁的实现
final boolean nonfairTryAcquire(int acquires) {
  final Thread current = Thread.currentThread();
  int c = getState();
  if (c == 0) {
    if (compareAndSetState(0, acquires)) {
      setExclusiveOwnerThread(current);
      return true;
    }
  }
  else if (current == getExclusiveOwnerThread()) {
    int nextc = c + acquires;
    if (nextc < 0) // overflow
      throw new Error("Maximum lock count exceeded");
    setState(nextc);
    return true;
  }
  return false;
}

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while(state 状态不允许获取) {
  if(队列中还没有此线程) {
    入队并阻塞
  }
}
当前线程出队

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if(state 状态允许了) {
  恢复阻塞的线程(s) 
}

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public interface Condition {

  // 一直等待可能抛出中断异常
  void await() throws InterruptedException;

  // 一直等待不会被中断异常打扰
  void awaitUninterruptibly();

  // 等待指定纳秒，期间可能抛出中断异常
  long awaitNanos(long nanosTimeout) throws InterruptedException;

  // 等待指定时间，期间可能抛出中断异常
  boolean await(long time, TimeUnit unit) throws InterruptedException;

  // 等待到指定时间，期间可能抛出中断异常
  boolean awaitUntil(Date deadline) throws InterruptedException;

  // 发送信号，解除任意一个等待
  void signal();

  // 发送信号，解除所有等待
  void signalAll();
}

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public class ThreadLocalDemo implements Runnable {
  private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>() {
    @Override
    protected Integer initialValue() {
      return 0;
    }
  };


  @Override
  public void run() {
    threadLocal.set(threadLocal.get()+1);
  }
}

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// 计算多行数字合
public class CountDownLatchDemo {

  private  CountDownLatch countDownLatch;

  private int storeNum[];

  public CountDownLatchDemo(final int numsLines) {
    this.countDownLatch = new CountDownLatch(numsLines);
    this.storeNum = new int[numsLines];
  }

  //计算每行数字合
  private void calc(int index, int calcNums[]){
    storeNum[index] = 0;
    for (int i = 0; i < calcNums.length; i++) {
      storeNum[index] += calcNums[i];
    }
    countDownLatch.countDown();
  }

  //总计
  private int calcSum() throws InterruptedException {
    countDownLatch.await();
    int result = 0;

    for (int i = 0; i < storeNum.length; i++) {
      result+= storeNum[i];
    }
    return result;
  }

  public static void main(String[] args) throws InterruptedException {

    CountDownLatchDemo countDownLatchDemo = new CountDownLatchDemo(nums.length);
    for (int i = 0; i < nums.length; i++) {
      int finalI = i;
      new Thread(new Runnable() {
        @Override
        public void run() {
          countDownLatchDemo.calc(finalI, nums[finalI]);
        }
      }).start();
    }
    int sum = countDownLatchDemo.calcSum();
    System.out.println(sum);
  }
}

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public CountDownLatch(int count) {
  if (count < 0) throw new IllegalArgumentException("count < 0");
  this.sync = new Sync(count);
}

Sync(int count) {
  setState(count);
}

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public void await() throws InterruptedException {
  sync.acquireSharedInterruptibly(1);
}

public final void acquireSharedInterruptibly(int arg) throws InterruptedException {
  if (Thread.interrupted())
    throw new InterruptedException();
  // tryAcquireShared(arg) ==》return (getState() == 0) ? 1 : -1;
  // 即当state不为0时进入，为0直接运行不阻塞
  if (tryAcquireShared(arg) < 0)
    doAcquireSharedInterruptibly(arg);
}

private void doAcquireSharedInterruptibly(int arg) throws InterruptedException {
  // 加入一个共享队列元素
  final Node node = addWaiter(Node.SHARED);
  boolean failed = true;
  try {
    for (;;) {
      final Node p = node.predecessor();
      if (p == head) {
        // tryAcquireShared(arg) ==》(getState() == 0) ? 1 : -1
        // 即如果是队列首元素就等待释放
        int r = tryAcquireShared(arg);
        if (r >= 0) {
          setHeadAndPropagate(node, r);
          p.next = null; // help GC
          failed = false;
          return;
        }
      }
      if (shouldParkAfterFailedAcquire(p, node) &&
          parkAndCheckInterrupt())
        throw new InterruptedException();
    }
  } finally {
    if (failed)
      cancelAcquire(node);
  }
}
}

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public class CyclicBarrierDemo {

  public void meet(CyclicBarrier cyclicBarrier){
    String threadName = Thread.currentThread().getName();
    System.out.println(threadName + " 到场 ");
    try {
      Thread.sleep(1000);
      cyclicBarrier.await();
    } catch (InterruptedException e) {
      // 当前线程被中断
      e.printStackTrace();
    } catch (BrokenBarrierException e) {
      // 不是被中断的线程，但是其它相关线程await()时发生中断
      e.printStackTrace();
    }
    System.out.println(threadName + " 准备开会发言");
  }

  public static void main(String[] args) {
    CyclicBarrierDemo cyclicBarrierDemo = new CyclicBarrierDemo();
    CyclicBarrier cyclicBarrier = new CyclicBarrier(5);
    for (int i = 0; i < 5; i++) {
      new Thread(new Runnable() {
        @Override
        public void run() {
          cyclicBarrierDemo.meet(cyclicBarrier);
        }
      }).start();
    }
  }
}

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public class SemaphoreDemo {

  private Semaphore semaphore = new Semaphore(5);

  public void doSomething() {
    try {
      /**
        * 在 semaphore.acquire() 和 semaphore.release()之间的代码，同一时刻只允许制定个数的线程进入，
        * 因为semaphore的构造方法是5，则同一时刻只允许5个线程进入，其他线程只能等待。
        **/
      semaphore.acquire();
      System.out.println(Thread.currentThread().getName() + ":doSomething start-" + new Date());
      Thread.sleep(2000);
      System.out.println(Thread.currentThread().getName() + ":doSomething end-" + new Date());
      semaphore.release();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

  public static void main(String[] args) {
    SemaphoreDemo service = new SemaphoreDemo();
    for (int i = 0; i < 20; i++) {
      new Thread(new Runnable() {
        @Override
        public void run() {
          service.doSomething();
        }
      }).start();
    }
  }
}

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// 每次计算完成交换结果
public class ExchangerTest {
  static class Producer extends Thread {
    private Exchanger<Integer> exchanger;
    private static int data = 0;
    Producer(Exchanger<Integer> exchanger) {
      super("Producer");
      this.exchanger = exchanger;
    }

    @Override
    public void run() {
      for (int i=1; i<5; i++) {
        try {
          TimeUnit.SECONDS.sleep(1);
          data = i;
          System.out.println(getName()+" 交换前:" + data);
          data = exchanger.exchange(data);
          System.out.println(getName()+" 交换后:" + data);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }
  }

  static class Consumer extends Thread {
    private Exchanger<Integer> exchanger;
    private static int data = 0;
    Consumer(Exchanger<Integer> exchanger) {
      super("Consumer");
      this.exchanger = exchanger;
    }

    @Override
    public void run() {
      while (true) {
        data = 0;
        System.out.println(getName()+" 交换前:" + data);
        try {
          TimeUnit.SECONDS.sleep(1);
          data = exchanger.exchange(data);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        System.out.println(getName()+" 交换后:" + data);
      }
    }
  }

  public static void main(String[] args) throws InterruptedException {
    Exchanger<Integer> exchanger = new Exchanger<Integer>();
    new Producer(exchanger).start();
    new Consumer(exchanger).start();
  }
}

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public class FutureDemo {

  private static class Product implements Callable<Product> {
    @Override
    public Product call() throws Exception {
      System.out.println("生成产品中...");
      Thread.sleep(5000);
      System.out.println("生成产品结束...");
      return new Product();
    }
  }

  public static void main(String[] args) {
    FutureTask<Product> futureTask = new FutureTask<>(new Product());
    // 使用FutureTask创建一个thread，FutureTask实现了Runnable接口
    Thread thread = new Thread(futureTask);
    // 启动线程任务
    thread.start();
    // 此时FutureTask任务在其它线程中执行，主线程不受影响
    System.out.println("干点其他事...");
    try {
      // 此时需要FutureTask任务执行的结果，会在此一直等候
      Product product = futureTask.get();
    } catch (InterruptedException e) {
      System.out.println("发生中断");
    } catch (ExecutionException e) {
      System.out.println("执行过程中发生异常 " + e.getMessage());
    }
  }
}