Java并发组件一之CountDownLatch
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使用场景:
一个或N个线程,等待其它线程完成某项操作之后才能继续往下执行。CountDownLatch描述的是,一个或N个线程等待其他线程的关系。
使用方法:
- 设CountDownLatch个数:CountDownLatch countDownLatch=new CountDownLatch(3);
- 在等待线程中await:countDownLatch.await();
- 在其他线程中减少count值:countDownLatch.getCount();
- 一旦其他线程中的countDownLatch.getCount()的次数为实例化时的count值,就唤醒等待线程
public class T06_TestCountDownLatch { public static void main(String[] args) { usingJoin(); usingCountDownLatch(); } private static void usingCountDownLatch() { Thread[] threads = new Thread[100]; CountDownLatch latch = new CountDownLatch(threads.length); for(int i=0; i<threads.length; i++) { threads[i] = new Thread(()->{ int result = 0; for(int j=0; j<10000; j++) result += j; latch.countDown(); }); } for (int i = 0; i < threads.length; i++) { threads[i].start(); } try { latch.await(); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("end latch"); } private static void usingJoin() { Thread[] threads = new Thread[100]; for(int i=0; i<threads.length; i++) { threads[i] = new Thread(()->{ int result = 0; for(int j=0; j<10000; j++) result += j; }); } for (int i = 0; i < threads.length; i++) { threads[i].start(); } for (int i = 0; i < threads.length; i++) { try { threads[i].join(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println("end join"); } }
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