/**
     * 當(dāng)網(wǎng)絡(luò)和代碼耗時高， 線程池再多， 一樣很快耗盡線程池；
     * 網(wǎng)絡(luò)和代碼耗時穩(wěn)定， 適度增加線程池?cái)?shù)量可提高單位時間內(nèi)任務(wù)處理量；
     */
    private static ExecutorService executorTask = new ThreadPoolExecutor(
            1,
            1,
            100L,
            TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<>(2),
            new ThreadPoolExecutor.CallerRunsPolicy());


    public static void main(String[] args) throws InterruptedException {

        Callable<String> callable = () -> {
            Thread.sleep(2000L);
            String tname = Thread.currentThread().getName();
            System.out.println(tname);

            return tname;
        };


        ArrayList<Callable<String>> callables = new ArrayList<>();


        for (int i = 0; i < 10; i++) {
            callables.add(callable);
        }

        executorTask.invokeAll(callables);

        executorTask.shutdown();
    }


       /*

      AbstractExecutorService


    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
        throws InterruptedException {
        if (tasks == null)
            throw new NullPointerException();
        ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
        boolean done = false;
        try {

          //在main線程循環(huán)任務(wù)隊(duì)列
          // CallerRunsPolicy卡住了， 循環(huán)任務(wù)隊(duì)列也會被卡主， 都是在main線程執(zhí)行
         
            for (Callable<T> t : tasks) {
                RunnableFuture<T> f = newTaskFor(t);
                futures.add(f);
                execute(f);
            }
            for (int i = 0, size = futures.size(); i < size; i++) {
                Future<T> f = futures.get(i);
                if (!f.isDone()) {
                    try {
                        f.get();
                    } catch (CancellationException ignore) {
                    } catch (ExecutionException ignore) {
                    }
                }
            }
            done = true;
            return futures;
        } finally {
            if (!done)
                for (int i = 0, size = futures.size(); i < size; i++)
                    futures.get(i).cancel(true);
        }
    }
    
    main線程中循環(huán)任務(wù)隊(duì)列
    把任務(wù)提交給子線程或任務(wù)隊(duì)列，如果隊(duì)列滿了， 或者沒有子線程接收任務(wù)， 
    則走拒絕策略， CallerRunsPolicy 在main線程執(zhí)行子任務(wù)， 因?yàn)闀ㄗain線程循環(huán)任務(wù)隊(duì)列。
    
    ThreadPoolExecutor

      public void execute(Runnable command) {
        if (command == null)
            throw new NullPointerException();

       int c = ctl.get();
        if (workerCountOf(c) < corePoolSize) {


        if (addWorker(command, true)) //  子線程中執(zhí)行任務(wù)
            return;
        c = ctl.get();
    }
        if (isRunning(c) && workQueue.offer(command)) {
        int recheck = ctl.get();
        if (! isRunning(recheck) && remove(command))
            reject(command); // main線程中執(zhí)行任務(wù)

        else if (workerCountOf(recheck) == 0)
            addWorker(null, false);
    }
        else if (!addWorker(command, false))
                reject(command);
   }



     */