java 并发编程实战闭锁（书上原文）_java教程

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java 并发编程实战闭锁（书上原文）

发布时间：2019-11-17 发布网站：脚本宝典

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使主线程高效地等待直到所有工作线程都执行完成，因此可以统计所消耗的时间。
                      PE="button" class="copyCode code-tool" data-toggle="tooltip" data-placement="top" data-clipboard-text="/**  * testHarness  *   * Using CountDownLatch for starting and stopping threads in timing tests  *  * @author brian Goetz and Tim Peierls  */ public class TestHarness {     public long timeTasks(int nThreads, final Runnable task)             throws InterruptedException {         final CountDownLatch startGate = new CountDownLatch(1);         final CountDownLatch endGate = new CountDownLatch(nThreads);          for (int i = 0; i < nThreads; i++) {             Thread t = new Thread() {                 public void run() {                     try {                         startGate.await();                         try {                             task.run();                         } finally {                             endGate.countDown();                         }                     } catch (InterruptedException ignored) {                     }                 }             };             t.start();         }          long start = System.nanoTime();         startGate.countDown();         endGate.await();         long end = System.nanoTime();         return end - start;     } }" title="" data-original-title="复制">       
       
/**  * TestHarness  * <p/>  * Using CountDownLatch for starting and stopping threads in timing tests  *  * @author Brian Goetz and Tim Peierls  */ public class TestHarness {     public long timeTasks(int nThreads, final Runnable task)             throws InterruptedException {         final CountDownLatch startGate = new CountDownLatch(1);         final CountDownLatch endGate = new CountDownLatch(nThreads);          for (int i = 0; i < nThreads; i++) {             Thread t = new Thread() {                 public void run() {                     try {                         startGate.await();                         try {                             task.run();                         } finally {                             endGate.countDown();                         }                     } catch (InterruptedException ignored) {                     }                 }             };             t.start();         }          long start = System.nanoTime();         startGate.countDown();         endGate.awaIT();         long end = System.nanoTime();         return end - start;     } }
 startGate.countDown() ，准备工作完成后，使所有工作线程开始工作；
 endGate.await() 使所有工作线程都执行完后，执行下面的代码。