停止线程池的正确方法

最后更新于：2022-08-13 12:47:15

1. shutdown

优雅的关闭线程池，会等待线程池内所有线程执行完毕，通知不再接收新的线程加入

示例

public class ShutDown {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newFixedThreadPool(1);
        for (int i = 0; i < 2; i++) {
            service.execute(new ShutDownTask());
        }
        Thread.sleep(1500);
        service.shutdown();
        System.out.println("shutDown");
        service.execute(new ShutDownTask());
    }
}

public class ShutDownTask implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            System.out.println(Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

运行结果

pool-1-thread-1
shutDown
Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task com.honor.concurrency.ThreadStop.ShutDownTask@6e0be858 rejected from java.util.concurrent.ThreadPoolExecutor@61bbe9ba[Shutting down, pool size = 10, active threads = 10, queued tasks = 0, completed tasks = 10]
    at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
    at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
    at com.honor.concurrency.ThreadStop.ShutDown.main(ShutDown.java:18)
pool-1-thread-1

2.isShutdown

查看线程池状态是否关闭，返回true或false,不代表线程已经结束，只是开始结束。

示例

public class ShutDown {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newFixedThreadPool(1);
        for (int i = 0; i < 2; i++) {
            service.execute(new ShutDownTask());
        }
        Thread.sleep(1500);
        System.out.println(service.isShutdown());
        System.out.println("shutDown");
        service.shutdown();
        System.out.println(service.isShutdown());
    }
}

class ShutDownTask implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            System.out.println(Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

运行结果

pool-1-thread-1
false
shutDown
true
pool-1-thread-1

3.isTerminated

查看线程是否已将完全结束

示例

public class ShutDown {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newFixedThreadPool(1);
        for (int i = 0; i < 2; i++) {
            service.execute(new ShutDownTask());
        }
        Thread.sleep(1500);
        System.out.println("shutDown:" + service.isShutdown());
        System.out.println("shutDown");
        service.shutdown();
        System.out.println("shutDown:" + service.isShutdown());
        System.out.println("Terminated:" + service.isTerminated());
        Thread.sleep(1000);
        System.out.println("Terminated:" + service.isTerminated());
    }
}

public class ShutDownTask implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            System.out.println(Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

运行结果

pool-1-thread-1
shutDown:false
shutDown
shutDown:true
Terminated:false
pool-1-thread-1
Terminated:true

4.awaitTermination

返回一段时间后，线程是否执行结束,并且调用了shutDown

示例

public class ShutDown {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newFixedThreadPool(1);
        for (int i = 0; i < 2; i++) {
            service.execute(new ShutDownTask());
        }
        System.out.println(service.awaitTermination(3, TimeUnit.SECONDS));
        service.shutdown();
        System.out.println(service.awaitTermination(3, TimeUnit.SECONDS));
    }
}

public class ShutDownTask implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            System.out.println(Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

运行结果

pool-1-thread-1
pool-1-thread-1
false
true

5.shutdownNow

强制中断线程，同时返回未执行的队列中的数据列表

示例

public class ShutDown {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newFixedThreadPool(1);
        for (int i = 0; i < 3; i++) {
            service.execute(new ShutDownTask());
        }
        Thread.sleep(1500);
        List runnables = service.shutdownNow();
        System.out.println("队列中剩余未执行线程数量" + runnables.size());
    }
}

public class ShutDownTask implements Runnable {
    @Override
    public void run() {
        String name = Thread.currentThread().getName();
        try {
            Thread.sleep(1000);
            System.out.println(name + "执行了");
        } catch (InterruptedException e) {
            System.out.println(name + "被中断了");
        }
    }
}

运行结果

pool-1-thread-1执行了
pool-1-thread-1被中断了
队列中剩余未执行线程数量1