ThreadPoolExecutor的使用 （獲取子線程執行結果后再執行主線程） 和CountDownLanch的簡要使用

一、ThreadPoolExecutor 簡要實例

  獲取子線程執行結果后再執行主線程 ，這樣可將復雜耗時業務拆分執行返回結果，將結果匯總整理。

多個線程時可以 利用Future阻塞，當其它線程執行完畢獲得結果，再執行主線程

/**
     * ThreadPoolExecutor 線程池使用
     * 1、多個線程時可以 利用Future阻塞，當其它線程執行完畢獲得結果，再執行主線程
      */
    @Test
    public void simpleMethod() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(9, 100, 100, TimeUnit.SECONDS, new SynchronousQueue<>());
        try {
            List<String> list1 = new ArrayList<String>();

            Callable<Integer> call1 = new Callable<Integer>() {
                @Override
                public Integer call() throws Exception {
                    for (int j = 0; j < 10; j++) {
                        list1.add("i:" + j);
                    }
                    return 10;
                }
            };
            Callable<Integer> call2 = new Callable<Integer>() {
                @Override
                public Integer call() throws Exception {
                    for (int j = 0; j < 10; j++) {
                        list1.add("i:" + j);
                    }
                    return 10;
                }
            };
            Callable<Integer> call3 = new Callable<Integer>() {
                @Override
                public Integer call() throws Exception {
                    for (int j = 0; j < 10; j++) {
                        list1.add("i:" + j);
                    }
                    return 10;
                }
            };

            Callable<Integer> call4 = new Callable<Integer>() {
                @Override
                public Integer call() throws Exception {
                    for (int j = 0; j < 10; j++) {
                        list1.add("i:" + j);
                    }
                    return 10;
                }
            };
            Future<Integer> f1 = poolExecutor.submit(call1);
            Future<Integer> f2 = poolExecutor.submit(call2);
            Future<Integer> f3 = poolExecutor.submit(call3);
            Future<Integer> f4 = poolExecutor.submit(call3);
            ArrayList<String> ss = new ArrayList<>();
            f1.get();
            f2.get();
            f3.get();
            f4.get();
            // Thread.sleep(1000);
            System.out.println("list1.size() = " + list1.size());
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

 

　二、CountDownLanch 簡要實例

場景：當指定幾個線程執行完后再執行 主線程，或使用2個CountDownLanch 對象進行多組子線程控制

/**
 * CountDownLatch  阻塞執行完預其的線程才會執行，后續方法業務處理
 */
@Test
public void lanchTest() {
    try {

        ThreadPoolExecutor thredPool = new ThreadPoolExecutor(20, 100, 1000, TimeUnit.SECONDS, new ArrayBlockingQueue<>(10));
        CountDownLatch cutdownLanch = new CountDownLatch(3);
        thredPool.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("我是子線程-id:" + Thread.currentThread().getName());
                cutdownLanch.countDown();
            }
        });

        thredPool.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("我是子線程-id:" + Thread.currentThread().getName());
                cutdownLanch.countDown();
            }
        });

        thredPool.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("我是子線程-id:" + Thread.currentThread().getName());
                cutdownLanch.countDown();
            }
        });
        System.out.println("這是主線程在下一句阻塞，current-thread-id:" + Thread.currentThread().getName());
        cutdownLanch.await();
        System.out.println("子線程執行完畢");

    } catch (InterruptedException e) {
        e.printStackTrace();
    }

}

ps: 線程池各參數 先估算，再加上壓力測試進行調整 。