IO密集型任务设置线程池线程数实现方式

class ThreadPoolTest {
 
    public static int PARK_TIME = 0;
 
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        runTask(1);
    }
 
    public static void runTask(int threadNum) throws ExecutionException, InterruptedException {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
            threadNum, threadNum, 1, TimeUnit.SECONDS, new LinkedBlockingDeque<>(100)
        );
 
        long start = System.currentTimeMillis();
        List<Future<?>> taskList = new ArrayList<>();
        for (int i = 0; i < 1; i++) {
            taskList.add(threadPoolExecutor.submit(() -> {
                doJob();
            }));
        }
        for (Future<?> future : taskList) {
            future.get();
        }
        long time = System.currentTimeMillis() - start;
        System.out.println(threadNum + "个线程，耗时：" + time + "停顿占比" + (PARK_TIME * 100.0 / time));
        threadPoolExecutor.shutdown();
    }
 
 
    public static Long doJob() {
        long result = 0L;
        PARK_TIME = 0;
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            if (i % 10_000_000 == 0) {
                try {
                    ++PARK_TIME;
                    // 模拟IO
                    LockSupport.parkNanos(100_000_000);
                } catch (Exception ignore) {
                }
            }
            result += i;
        }
        return result;
    }
}

class ThreadPoolTest {
    
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        List<Integer> threadNumList = Arrays.asList(4, 8, 16, 25, 34, 50);
        for (Integer threadNum : threadNumList) {
            runTask(threadNum);
        }
    }
 
    public static void runTask(int threadNum) throws ExecutionException, InterruptedException {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
            threadNum, threadNum, 1, TimeUnit.SECONDS, new LinkedBlockingDeque<>(100)
        );
 
        long start = System.currentTimeMillis();
        List<Future<?>> taskList = new ArrayList<>();
        for (int i = 0; i < 55; i++) {
            taskList.add(threadPoolExecutor.submit(() -> {
                doJob();
            }));
        }
        for (Future<?> future : taskList) {
            future.get();
        }
        long time = System.currentTimeMillis() - start;
        System.out.println(threadNum + "个线程，耗时：" + time);
        threadPoolExecutor.shutdown();
    }
 
 
    public static Long doJob() {
        long result = 0L;
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            if (i % 10_000_000 == 0) {
                try {
                    LockSupport.parkNanos(100_000_000);
                } catch (Exception ignore) {
                }
            }
            result += i;
        }
        return result;
    }
}