小记：executor.shutdownNow无法关闭线程池，线程池卡死

一定要注意子线程的InterruptedException异常处理，要throw出来，不要吞掉！
正确案例：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class Demo {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(2);
        executorService.submit(new SubThread());
        executorService.submit(new SubThread());
        executorService.shutdown();
        try {
            if (!executorService.awaitTermination(5, TimeUnit.SECONDS)) {
                System.out.println("线程池关闭超时");
                executorService.shutdownNow();
                if (!executorService.awaitTermination(3, TimeUnit.SECONDS)) {
                    System.out.println("线程池强制关闭失败");
                } else {
                    System.out.println("线程池强制关闭成功");
                }
            } else {
                System.out.println("线程池关闭成功");
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}
class SubThread implements Runnable {
    @Override
    public void run() {
        while (true) {
            System.out.println(Thread.currentThread().getName());
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                // 抛出异常
                throw new RuntimeException(e);
            }
        }
    }
}
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错误案例：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class Demo {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(2);
        executorService.submit(new SubThread());
        executorService.submit(new SubThread());
        executorService.shutdown();
        try {
            if (!executorService.awaitTermination(5, TimeUnit.SECONDS)) {
                System.out.println("线程池关闭超时");
                executorService.shutdownNow();
                if (!executorService.awaitTermination(3, TimeUnit.SECONDS)) {
                    System.out.println("线程池强制关闭失败");
                } else {
                    System.out.println("线程池强制关闭成功");
                }
            } else {
                System.out.println("线程池关闭成功");
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}
class SubThread implements Runnable {
    @Override
    public void run() {
        while (true) {
            System.out.println(Thread.currentThread().getName());
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                // 没有抛出异常，线程池将卡死，无法退出
                e.printStackTrace();
            }
        }
    }
}
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