CountDownLatch
- CountDownLatch是一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。
private static final CountDownLatch rongYao = new CountDownLatch(5);
static class Hero implements Runnable {
@Override
public void run() {
try {
Thread.sleep(new Random().nextInt(10) * 1000);
System.out.println("--> 英雄：" + Thread.currentThread().getName() + " 准备开始战斗.....");
rongYao.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private static void testCountDownLatch() throws InterruptedException {
// CountDownLatch测试
Thread thread1 = new Thread(new Hero(), "鲁班七号");
Thread thread2 = new Thread(new Hero(), "程咬金");
Thread thread3 = new Thread(new Hero(), "黄忠");
Thread thread4 = new Thread(new Hero(), "凯");
Thread thread5 = new Thread(new Hero(), "嬴政");
System.out.println("--> 所有英雄准备开始战斗....");
System.out.println();
thread1.start();
thread2.start();
thread3.start();
thread4.start();
thread5.start();
rongYao.await();
System.out.println("--> 所有英雄都准备好了，开撸吧...");
System.out.println();
}
- CyclicBarrier是一个同步辅助类，允许一组线程互相等待，直到到达某个公共屏障点 (common barrier point)。因为该 barrier 在释放等待线程后可以重用，所以称它为循环 的 barrier。
private static final CyclicBarrier cyclicBarrier = new CyclicBarrier(5, () -> System.out.println(">>>>>>>>>>>>>>>>>> 一个阶段完成 <<<<<<<<<<<<<<<<<"));
private static final CountDownLatch cr = new CountDownLatch(5);
static class Hero1 implements Runnable {
@Override
public void run() {
try {
Thread.sleep(new Random().nextInt(5) * 1000);
System.out.println("--> 英雄：" + Thread.currentThread().getName() + " 已经到达中路，请求出击.....");
cyclicBarrier.await();
Thread.sleep(new Random().nextInt(10) * 1000);
System.out.println("--> 英雄：" + Thread.currentThread().getName() + " 战胜了对手.....");
cyclicBarrier.await();
Thread.sleep(new Random().nextInt(3) * 1000);
System.out.println("--> 英雄：" + Thread.currentThread().getName() + " 已经回城.....");
cr.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}
}
private static void testCyclicBarrier() throws InterruptedException {
// CountDownLatch测试
Thread thread1 = new Thread(new Hero1(), "鲁班七号");
Thread thread2 = new Thread(new Hero1(), "程咬金");
Thread thread3 = new Thread(new Hero1(), "黄忠");
Thread thread4 = new Thread(new Hero1(), "凯");
Thread thread5 = new Thread(new Hero1(), "嬴政");
System.out.println("--> 中路战斗准备开始....");
System.out.println();
thread1.start();
thread2.start();
thread3.start();
thread4.start();
thread5.start();
cr.await();
System.out.println("--> 中路战斗结束...");
}
- Semaphore是一个计数信号量，它的本质是一个"[共享锁]"。
信号量维护了一个信号量许可集。线程可以通过调用acquire()来获取信号量的许可；当信号量中有可用的许可时，线程能获取该许可；否则线程必须等待，直到有可用的许可为止。 线程可以通过release()来释放它所持有的信号量许可。
private static final Semaphore semaphore = new Semaphore(5);
private static void testSemaphore() {
for (int i = 0; i < 10; i ++) {
new Thread(new Runnable() {
@Override
public void run() {
try {
if (semaphore.tryAcquire(1, new Random().nextInt(10), TimeUnit.SECONDS)) {
Thread.sleep(new Random().nextInt(10) * 1000);
System.out.println(Thread.currentThread().getName() + " 获取到了执行的机会，已经完成了要做的工作...");
} else {
System.out.println(Thread.currentThread().getName() + " 在等待了一会之后没有获取到CPU资源，退出了...");
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
semaphore.release();
}
}
}, "thread--" + i).start();
}
}
