concurrent test

whatsmars-common/src/test/java/org/hongxi/java/util/concurrent/CountDownLatchTest2.java

+package org.hongxi.java.util.concurrent;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * @author shenhongxi 2019/8/11
+ *
+ * @see JoinTest
+ * @see InvokeAllTest
+ */
+public class CountDownLatchTest2 {
+
+    public static void main(String[] args) {
+        int nThreads = 3;
+        CountDownLatch latch = new CountDownLatch(nThreads);
+        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
+        long begin = System.currentTimeMillis();
+        for (int i = 0; i < nThreads; i++) {
+            executorService.submit(new Task(i + 1, latch));
+        }
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        System.out.println(System.currentTimeMillis() - begin);
+        executorService.shutdown();
+    }
+
+    static class Task implements Runnable {
+        private int id;
+        private CountDownLatch latch;
+
+        Task(int id, CountDownLatch latch) {
+            this.id = id;
+            this.latch = latch;
+        }
+
+        @Override
+        public void run() {
+            try {
+                Thread.sleep(1000 * id);
+                System.out.println(String.format("Sub Thread %d finished", id));
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            } finally {
+                latch.countDown();
+            }
+        }
+    }
+}