Java 多線程 CountDownLatch 試用

簡述：

使用Java多線程的庫，包括

ExecutorService線程池，

CountDownLatch線程運行控制（知道全部啓動的線程調用完成後，函數纔會繼續執行）

[java]  view plain copy

1. package test.anialy.multithread;  
2.   
3. import java.util.Random;  
4. import java.util.concurrent.CountDownLatch;  
5. import java.util.concurrent.ExecutorService;  
6. import java.util.concurrent.Executors;  
7. import java.util.concurrent.atomic.AtomicInteger;  
8. import java.util.concurrent.atomic.AtomicLong;  
9.   
10. import org.junit.Test;  
11.   
12. public class MultiThreadCountTest  {  
13.   
14.     // 線程處理函數  
15.     public static void doSomething() {  
16.         try {  
17.             Thread.sleep(new Random().nextInt(10));  
18.         } catch (InterruptedException e) {  
19.             e.printStackTrace();  
20.         }  
21.     }  
22.   
23.     @Test   
24.     public void main() throws Exception {  
25.         final int currency = 10; // 線程池大小  
26.         ExecutorService service = Executors.newFixedThreadPool(currency);  
27.   
28.         final AtomicInteger successThreadCnt = new AtomicInteger(0);  
29.         final AtomicLong totalCost = new AtomicLong(0);  
30.   
31.         int count = 100; // 執行次數  
32.         // 全部線程結束  
33.         final CountDownLatch block = new CountDownLatch(count);    
34.   
35.         for (int i = 0; i < count; i++) {  
36.             service.execute(new Runnable() {  
37.                 @Override  
38.                 public void run() {  
39.                     try {  
40.                         long start = System.currentTimeMillis();  
41.                         // 執行某個函數操做  
42.                         doSomething();  
43.                         totalCost.addAndGet(System.currentTimeMillis() - start);  
44.                         successThreadCnt.incrementAndGet();  
45.                     } catch (Exception e){  
46.                         e.printStackTrace();  
47.                     } finally {  
48.                         block.countDown();  
49.                     }  
50.                 }  
51.             });  
52.         }  
53.   
54.         block.await();  
55.   
56.         System.out.printf("共%s次觸發函數doSomething,併發%s,成功%s個,平均耗時: %d ms",  
57.                 count,  
58.                 currency,  
59.                 successThreadCnt.get(),  
60.                 totalCost.get() / successThreadCnt.get());  
61.     }  
62. }  

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